20 5 



I may now summarise the evidence as to the influence of 

 heredity on these malarial diseases as follows : The real 

 nature of the potential causative agent, malaria, is unknown : 

 obviously, however, it is communicated to the system from 

 without. Its effects differ in different individuals, but as 

 they have been known to exist from the most primitive 

 times, so they have become so inbred into the human race 

 that comparatively few of us are totally exempt. Thus a 

 diathesis has been developed which might almost be 

 included with those termed " universal " viz., the catarrhal, 

 the rheumatic, and the scrofulous. Moreover, in addition 

 to this racial peculiarity, many individuals are especially 

 predisposed to the influence of malaria by heredity, and this 

 .can all the more easily be understood when we remember 

 that each individual who has suffered from malaria has his 

 tissues branded with it during his life ; and the probability 

 is that with the amount of diathetic peculiarity which he has 

 in common with most inherited, he will also transmit a 

 thus intensified personal predisposition to his children. 

 Given an individual who has suffered severely from any 

 variety of malarial disease, he must in the first instance 

 have himself been specially predisposed before being 

 attacked, and if the law of heredity holds good at all, it 

 assuredly follows that, c&teris paribus. he may transmit this 

 predisposition, if not the actual disease, to his offspring. 



I have still, however, to consider the third division of the 

 acute infectious diseases viz., those which may be said to 

 be miasmatic-contagious, which, as they cannot be conveyed 

 from diseased to healthy individuals by mere contact, are 

 not contagious according to the significance of the term, and 

 on the other hand, the poison has the characteristic 

 peculiarity of the miasmatic diseases in being, in the first 



