easily become the possessions of families or of race. Not 

 only do individuals differ in the degree of reflex susceptibility, 

 but they also vary much as to the special tissues or organs 

 which are most prone to suffer under it. Thus, some catch 

 cold almost solely in the mucous membrane of the nasal pass- 

 ages and pharynx; in others, the tonsils, throat, and larynx are 

 much more prone to suffer ; in others, the bronchial mucous 

 membrane, etc." To these two diatheses, therefore, I trace 

 the heredity of the majority of the diseases of the respira- 

 tory system, for it will be found that by far the greater num- 

 ber of them are included under the heads of scrofulous or 

 other well-recognised constitutional and heritable conditions, 

 and under that of the universally-developed catarrhal dia- 

 thesis. Thus under the head of scrofulous diathesis may be 

 included chronic tubercular phthisis, acute miliary tuber- 

 culosis, pleural tuberculosis, and, perhaps, gangrene of the 

 lungs ; whilst under that of the catarrhal diathesis we may 

 range croupous and catarrhal pneumonia, croupous or 

 fibrinous bronchitis, bronchitis, croup, coryza, rhinitis blen- 

 norrhoica, acute and chronic laryngitis, catarrhal tracheitis, 

 bronchial catarrh, pleuritis, tonsillitis, etc. In this list I do 

 not include pulmonary emphysema, and bronchial asthma, 

 which are, however, well-known to be hereditary. Various 

 other so-called diseases of the respiratory organs might be 

 mentioned, as pneumo-thorax, hydro-thorax, haemoptysis, 

 atelectasis (often congenital), oedema, etc., but as these are 

 for the most part merely symptomatic of other diseases, I 

 shall not now further allude to them. 



What I am contending for is not that all the diseases of 

 the respiratory system are hereditary or heritable as such, 

 but that in the case of each of them there is a predisposi- 

 tion which is inherited by every individual affected by them ; 



