192 ACQUIRED CHARACTERS SEC. 



definite changes in the brain, and to a certain degree definite 

 and capable of hereditary transmission) that a morbid state 

 of the brain which may have melancholia as a result (if 

 external conditions occur which excite its outbreak) is 

 acquired and transmitted by a human being provided with 

 nerves and brain. 



It is also intelligible that such a condition may be acquired 

 through union with another sexual cell, provided that one or 

 both of the uniting sexual cells possess the acquired and 

 inherited tendency thereto. 



It is, however, perfectly inconceivable, if the living world 

 be regarded as a continuous whole, that such a condition 

 should ever have come about without acquirement and 

 inheritance. 



Mental capacity is an acquirement, and mental diseases 

 are diseases of relation. 



As for the rest, it is certain that not only mere general 

 morbid conditions of the nervous system are inherited, but 

 also definite tendencies to mental disease, and likewise 

 definite mental abilities. The terms by which we express 

 both are of less importance, for, by the nature of the case, 

 these are only too often more or less artificial and elastic 

 (conventional). 



It is obvious that the mechanism of the human brain 

 has become by acquirement so delicate that a high degree 

 of division of labour has taken place in it, which can only 

 depend on the fact that definite groups of brain-cells each 

 exercise and can only exercise definite functions. These 

 groups form " centres " which have assumed not the simplest 

 of such functions, elementary functions, but those of more 

 compound character, often indeed those which respond to the 

 demands of recently-developed civilisation. 



I appeal, therefore, not to the numerous physiological 

 experiments which, by the aid of the results of pathological 



