generations. The phenomenon in this case, nervous in 

 character, is induced purely by mental shocks acting defi- 

 nitely, but in so refined a manner, on the heart, that we as 

 yet know nothing of the physical change that is developed 

 in the nervous matter. Again, I have known families in 

 whom the tendency to some forms of communicable disease 

 has been markedly apparent, and I have known instances of 

 the reverse. Thus I have seen hereditary proclivity to 

 scarlet fever and to diphtheria. I have also seen, in respect 

 to one of these diseases (scarlet fever) hereditary opposition 

 to it, if the term be allowable." 



There can at least be no doubt that peculiarities of 

 formation, and the tendency to particular affections, are 

 transmitted in families from one generation to another ; so 

 that in one family will be recognised a peculiar form of the 

 head, predisposing to inflammation of the brain, madness, 

 epilepsy, paralysis, apoplexy, etc. ; in a second family may be 

 found a remarkable formation of the chest, leading to con- 

 sumption ; in a third family may be found a peculiarity of 

 structure, predisposing to disorders and diseases of the 

 heart ; in a fourth an innate tendency to derangement or 

 disease of the stomach, liver, and bowels ; and in a fifth a 

 predisposition to diseases of the skin ; whilst in large families 

 it may be found that some of the members have been prone 

 to affections of certain organs, from generation to generation. 

 These hereditary physical peculiarities are sometimes con- 

 nected with peculiar conditions of the nervous system, but 

 more frequently of the capillary portion of the circulatory 

 system. 



Discarding all accepted lists of hereditary diseases as 

 such, I now propose to pass in rapid review the principal 

 diseases of the human body, in connection with the organic 



