CHAPTER Y. 



Heredity. 



I NOW propose to make some further remarks on the subject of 

 heredity, as we are in a position to form a just estimate of the 

 extent of its influence in the causation of disease. 



There can be no doubt — and I say this emphatically — that 

 pathologists do not sufficiently recognize the important part 

 played by heredity in disease. Yet mankind in general, without 

 seeking for the why or the wherefore, tacitly acknowledges its 

 potent influence in determining the conformation of mind and 

 body. In respect of the latter, it has been recognized by 

 breeders of animals, as Darwin is so careful to insist, since 

 time immemorial ; and as regards its influence on the mental 

 portion of our being, we have only to study biographies and 

 works of fiction to see how well the writers have understood 

 its significance. 



In nothing, perhaps, is the influence of heredity more 

 manifest than in the evolution of the moral faculty, and 

 this branch of the subject has been thoroughly discussed 

 by Herbert Spencer, who demonstrates how the finer shades 

 of moral faculty have been, and are now being, evolved. 

 Man being a social animal, it is necessary for him to observe 

 certain rules of conduct towards his fellows. If lying, and 

 theft are accepted practices, no social community can exist, 

 except in an inchoate condition ; therefore, the social community 

 of which man forms part must be bound together by certain 

 ties of mutual conduct, such ties constituting "a code of 

 morality." Generation after generation of men being thus 

 compelled to observe certain rules of conduct towards one 

 another, the moral faculty gradually rises into being : it 

 begins to exist, that is to say, independently of inculcation, 

 although, of course, capable of being strengthened and 



