1 84 A REMARKABLE ANTICIPATION OF 



a clear proof of the hereditary nature of acquired states 

 of the constitution '. 



Against such a view he contends that any particular 

 disease can only follow when there exists * a preparation, 

 laid in the first place by nature, in the original stamina 

 and habit of the body ' ; and he points out that the same 

 hurtful cause may produce quite distinct diseases. Thus 

 ' intemperate living ... is commonly said to bring on, in 

 one person, a predisposition to gout, in another to diseases 

 of the liver, or of the stomach, or of the brain. Now, 

 since the difference is not in the external causes, it must 

 be in the natural peculiarities of the constitutions on 

 which they act. These, therefore, are previously fitted by 

 original organization to take on them one form of morbid 

 affection rather than another. It is then clear that the 

 predisposition is laid by natural or congenital structure, 

 in the first instance '. Individuals differ in particular 

 organs ; the exciting causes of disease bring out the 

 weaknesses which previously existed and might other- 

 wise have remained unknown. Such defects ' being a part 

 of the original bodily structure ' are hereditary. ' The 

 first individual who exposes himself to the morbid causes, 

 first betrays the peculiar defect of the race, and is thus 

 erroneously supposed to lay the foundation for it.' 



Syphilis, which appears to be an exception, he explains 

 by ' a peculiar mode of infection. . . . This is evidently 

 a phaenomenon of a very different kind from the simi- 

 larity of structure which the laws of nature have ordained 

 between parents and their offspring '. 



Hence he infers ' that the phenomena of predisposition 

 to diseases rather confirms than invalidates the general 

 observations before laid down, and we may be allowed to 

 conclude, that no acquired varieties of constitution become 

 hereditary, or in any manner affect the race '. 



The preservation of complexion after a race has 

 migrated to a very different climate conforms to the 

 general law. Although the parents may alter greatly, 

 ' the adventitious colour has no influence on the offspring '. 



Hence in looking for the causes of varieties of mankind 

 we must not ' direct our attention to the class of external 



