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Concerning the innate disposition in the skin tissues 

 themselves to take on a diseased condition, it is pretty 

 certain, as Dr. Tilbury Fox observes, that many diseases of 

 the skin must originate in a disordered behaviour of the 

 tissues themselves, and do not necessarily depend for their 

 cause upon any general defect of nutrition. For instance, 

 cancer is a case in point ; and so also warty growths of all 

 kinds, fibroma, keloid, and perhaps lupus, are other illustra- 

 tions of the same thing. In some cases there is just an 

 excess of growth, a plus state of the nutrition of the tissue, 

 and nothing more (hypertrophic) ; or it may be a minus 

 condition (atrophic). In other instances it is a perverted 

 nutrition, a deviation in the type of the tissue, as in cutaneous 

 cancer. The epithelial layers may be mainly affected, as 

 in warts, corns, xeroderma, and ichthyosis, or the connective 

 tissues of the skin may be specially involved, as in keloid, 

 fibroma, morphoea, and scleroderma. Moreover, all the 

 diseases of the sweat glands and follicles of the sebaceous 

 glands of the hair and hair follicles, and of many of 

 those of the nails, belong to the same category, and are all 

 subject to the influence of heredity. 



As showing how predisposition and insusceptibility both 

 of which I have elsewhere proved to be more or less the 

 result of heredity may influence parasitic diseases of the 

 skin, I may here quote from Dr. Alder Smith, who says : 

 " All children are not equally susceptible to ringworm. A 

 certain unknown condition of the skin is necessary for the 

 growth of the fungus. Some children never take ringworm, 

 though certainly liable to become infected ... On some 

 the fungus takes but slight hold, and is easily destroyed ; 

 others again appear to be extremely susceptible . . . The 

 difference in these cases must depend on some peculiar 



