144 



with only in the scrofulous. " How this inherited diathesis," 

 says Ruehle, 1 "is produced, or what is its real nature, are 

 questions beyond our present knowledge; but if the 

 external form of the body, and mental qualities, can be 

 transmitted in families through generations, why should 

 this not be the case also with the conditions which produce 

 a disposition to certain diseases ? If in the former case 

 we do not demand that the comparison be made only 

 between children and their parents, but include also the 

 grandchildren and nephews, why should we not observe 

 the same rule in regard to the inheritability of disease ? 

 Why do we narrow the question to asking whether the 

 father or the mother is known to have the same disease at 

 the time of conception ? Is not a disease often present 

 before it can be recognised ? May there not be a dis- 

 position sufficient to be transmitted, although it does not 

 manifest itself as a recognisable disease until afterwards ? " 

 In answer to such questions as these, I unhesitatingly reply 

 to each of them in the affirmative. For, in the first place, 

 as heredity is a law of our being, and as the material,, 

 functional, and dynamical peculiarities of ancestors and 

 parents are transmitted by them to their descendants, it 

 assuredly follows that the conditions which produce a pre- 

 disposition to any morbid process are also transmissible. 

 We are too liable to narrow down the question of hereditary 

 descent as if affecting only the qualities inherited by a. 

 child from his parents, whereas it is a matter affecting 

 the evolution of the race. Every living individual has 

 been dependent upon some other or others as far back as 

 the history of man is recorded by the hand of time ; for 

 has not every unit of the human family originally sprung 



1 Ziemssen, vol. v. 



