72 HEREDITY AND SELECTION IN SOCIOLOGY 



Undoubtedly the condition of the brain structure in the ofispring 

 — supposing the pathological condition of which epilepsy is a 

 manifestation to be hereditary — ^is not the normal condition; 

 but the injury to the skull, which was the original cause 

 of the disease in the parent, is not handed down to the child. 

 Should, therefore, traumatically induced epilepsy be hereditary 

 — which is questionable — it would seem that it is not the 

 actual disease itself, but a predisposition to it, which is trans- 

 mitted. 



That traumatically induced epilepsy, if hereditary, should 

 contradict the contention that somatically acquired characters 

 are not hereditary is an entirely incorrect assumption. For the 

 actual injury itself is not transmissible ; it remains a purely 

 somatic, an exclusively individual, phenomenon. The efiect of 

 the injury would alone be transmissible ; and it is not more 

 difficidt to conceive of so profound a disturbance of the psychical 

 life exerting an influence by reaction on the reproductive organs 

 than to conceive of a similar reaction in the case of tuberculosis, 

 which involves a profound disturbance of the physical hfe of the 

 organism. It must be repeated, however, that the experiments 

 of Brown-Sequard, supposed to prove the hereditary transmis- 

 sion of traumatically induced epilepsy, are by no means either 

 conclusive or convincing. 



It is frequently said that " instincts are but inherited habits," 

 and by this definition it is held that the phenomena of instinct 

 are explained. Habits, in the course of individual life, tend to 

 become automatic ; and it is maintained that this acquired 

 automatism, transmitted by heredity, has developed into instinct, 

 which thus presents the appearance of being a priori ; whereas 

 such instincts, although a priori in every individual after a 

 certain time, are not a priori in the sense of being anterior to 

 all individual experience. 



To this conception of instinct as an " inherited habit " there 

 is a fundamental objection which relates to cases in which all 



