CHAPTER VII 



THE INHERITANCE OF DISEASE 



Though in practice we may distinguish between health and 

 disease, there is in reahty no sharp division between them. 

 Nature does not care about any such categories as we may 

 put up in the abstract. Indeed, the arguments on the 

 inheritance of disease would fall naturally under the 

 different heads we have discussed in the previous 

 chapter. 



If we discuss diseases separately, it is merely in order 

 to give greater emphasis to a subject of such vital 

 and practical importance. 



I.— GENERAL ARGUMENTS. 



The general arguments about the inheritance of disease 

 resolve themselves very much on the question whether such 

 are inheritable or not. In other words, we have the dis- 

 cussion once more whether acquired characters — in our 

 instance, acquired diseases — are inherited or not. For this 

 purpose we have to discriminate, as previously, which 

 diseases are acquired and which inborn. 



[a) Congenital Diseases. 



We must in the first instance carefully distinguish be- 

 tween congenital diseases and diseases inborn. Con- 

 genital diseases may be inborn or they may be acquired 



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