CHAPTER III. 



HEREDITY OF DISEASES. 



ANY abnormal peculiarities of the animal organi- 

 zation, constituting disease, whether of structure or 

 function, are liable to be transmitted from parent to 

 offspring. 



"When a disease is characterized by obvious struct- 

 ural changes in any part of the system, its heredity 

 is seldom called in question ; but when it consists in a 

 simple derangement of function, without any apparent 

 indications of structural transformation, its hereditary 

 character is frequently overlooked. As the progress 

 of physiological science, however, makes us better 

 acquainted with the minute structure of the various 

 organs of the body, and the relations of such structure 

 to their activity, the cases of functional disturbance 

 that are not known to be accompanied by correspond- 

 ing changes in structure have rapidly diminished, and 

 that to so great an extent that it seems probable that 

 all indications of disease are the result of some struct- 

 ural modification of the organs involved. 



The hereditary transmission of some peculiarity in 

 the performance of the function of an organ, without 

 apparent structural change, is perhaps not more diffi- 

 cult to understand than the heredity of habits that, in 



