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diseases which are the most assuredly and markedly 

 hereditary, none are more so than those of a degenerative 

 form, including structural heart diseases, atheromatous 

 vessels, emphysema, certain diseases of kidney, etc. All 

 these partake of the nature of premature senility of organ 

 or tissue, consequent upon some inherent deficiency in 

 their vitality. " Although the constitution of an individual 

 begins with his life, it is nevertheless the resultant of the 

 constitutional peculiarities of many antecedents. This being 

 so, tendencies to disease may date far back in the pedigree, 

 to be called forth from time to time by favouring circum- 

 stances." What we have practically to remember is, that in 

 addition to such definite inherited forms of disease as 

 congenital syphilis, gout, scrofula, tuberculosis, cancer, 

 asthma, and several neuroses, the relative soundness or 

 unsoundness of individual constitutions is also dependent 

 upon a local or general defectiveness of vitality, which is 

 hereditary, and which will tend to develop disease in the 

 impaired organ or tissue. Constitutions are liable to be 

 rendered unsound, not only by definite inherited forms of 

 disease and defective vitality, but by the wear and tear of life 

 in its environment. Here again we have the constitutional 

 vigour so impaired, subsequently to birth, by pernicious 

 surroundings, that constitutional diseases are thus engendered 

 and passed down as a legacy to be inherited in future 

 generations, in the form of scrofula, rickets, phthisis, etc. 1 



We thus see that there is no organ or tissue of the human 

 body which is not subject to heredity in disease as in 

 health : the fact being that, in one as in the other, like 

 begets a predisposition to like, capable of being modified 

 by variability, or even neutralised by marriage into a new 

 1 Dr. Douglas Powell. 



