Characters, Hereditary and Acquired. 81 



this reflex is congenital, or not acquired during the 

 life-time of each individual dog. Now, although the 

 action of scratching is doubtless adaptive, it appears 

 to me incredible that it could ever have become 

 organized into a congenital reflex by natural selec- 

 tion. For, in order that it should, the scratching 

 away fleas would require to have been a function of 

 selective value. Yet, even if the irritation caused by 

 fleas were supposed to be so far fatal in the struggle 

 for existence, it is certain that they would always be 

 scratched away by the conscious intelligence of each 

 individual dog ; and, therefore, that no advantage 

 could be gained by organizing the action into a 

 reflex. On the other hand, if acquired characters 

 are ever in any degree transmitted, it is easy to 

 understand how so frequently repeated an action 

 should have become, in numberless generations of 

 dogs, congenitally automatic. 



So much for the general principle of selective 

 value as applied to this particular case. And simi- 

 larly, of course, we might here repeat the application 



newly-born individuals — i.e. before the animals were able to co-ordinate 

 their movements, and therefore before they had ever even attempted to 

 scratch themselves. Notwithstanding that they were thus destitute of 

 individual experience with regard to the benefit of scratching, they began 

 their scratching movements with their stumps as soon as they were 

 capable of executing co-ordinated movements, and afterwards continued 

 to do so till the end of their lives with as much vigour and frequency as 

 nnmutilated animals. Although the stumps could not reach the seats 

 of irritation which were bent towards them, they used to move rapidly 

 in the air for a time sufficient to have given the itching part a good 

 scratch, had the feet been present — after which the animals would resume 

 their sundry other avocations with apparent satisfaction. These facts 

 showed the hereditary response to irritation by parasites to be so strong, 

 that even a whole life-time's experience of its futility made no difference 

 in the frequency or the vigour thereof. 



TI. G 



