PREDISPOSITIONS TO DISEASE 267 



in human life we may mention those which result in abnormal 

 nervous processes, in rheumatism with its many forms, in gout, 

 in obesity, in tendency to stone or gravel, in asthma, and so on. 

 The reappearance of these diseases in varying degrees is certain, 

 but what is really transmitted is the original germinal irregularity 

 of gearing. No one can explain what this irregularity precisely 

 is, but it is a common experience, baffling to the physician, 

 that if it is adroitly checked in its outcrop in one direction it 

 may manifest itself in another. He may cure the disease, 

 but he cannot reconstitute his patient. Hydra-headed, the 

 predisposition will show itself in polymorphic guise. 



Some men are immune to certain diseases — e.g. to scarlet fever ; 

 all men are immune to fowl-cholera and many other animal 

 diseases. This immunity is mysterious, but it is not " mystical." 

 Of recent years we have begun to understand it, to measure it. 

 And "predisposition" is the other side of immunity. 



It is probable that some " predispositions " are much more 

 definite than others. Thus, haemophilia may be due to a re- 

 trogressive variation comparable to albinism ; some particular 

 item in the normal inheritance has been suppressed or kept 

 latent. But the predisposition to tuberculosis is probably much 

 less definite, and due to a more general disturbance of the 

 " protoplasmic gearing," which finds multiple expressions both 

 structural and functional. 



The predisposition to gout is well known to be hereditary. 

 It is probably what may be called a general constitutional 

 predisposition, involving a derangement of the normal meta- 

 bolism. For while it perhaps finds its primary expression in 

 peculiarities of the digestive and excretory organs, it may affect 

 practically every tissue in the body. Its expression may be 

 accelerated by luxurious living and laziness, but, given the 

 predisposition, it may manifest itself in those who live very 

 carefully and take plenty of exercise. That is the peculiar 

 hardship of it ! 



