292 HEREDITY AND DISEASE 



or it may be that the son is asthmatic. An alcoholic patient 

 may have an epileptic child. A tubercular mother may have 

 a child with Pott's disease. A man infected with syphilis may 

 have a son afflicted with general paralysis. In regard to the 

 last case, it may be, as has been recently suggested, that even 

 general paralysis has its associated micro-organism, which finds 

 a suitable soil in syphilised tissues. It is probable, at all events, 

 that syphilis is one of the predisposing causes of general paralysis. 



It is easj' to add to these illustrations. " An inheritance from 

 a parent who has suffered from psoriasis may possibly be trans- 

 mitted as ichthyosis, or some form of chronic eczema or lichen " 

 (Hutchinson, 1896, p. 66). A man with tabes may beget a 

 child with epilepsy. An eye defect, such as microphthalmia, 

 may be represented in the offspring by quite a different ab- 

 normality. Perhaps the best examples of change of outcrop are 

 furnished by nervous disorders. Convulsions in one generation 

 may be represented by hysteria in the next, or hyperesthesia 

 by mania, or insanity by epilepsy, and so on. 



As Prof. F. W, Mott says, speaking from a wide knowledge of 

 nervous diseases : " It is not necessarily insanity that is inherited, 

 but a neuropathic tendency in the stock which manifests itself 

 in many forms, e.g. epilepsy, asthma, migraine, chorea, diabetes, 

 exophthalmic goitre, neurasthenia, eccentricity, hysteria, crimin- 

 ality, fanaticism, suicide, genius of a certain type, and insanity " 

 (1911, p. 80). 



It may appear for a moment that these illustrations prove too 

 much, suggesting as they do that the inheritance of morbid pre- 

 dispositions is very inconstant. But it must be noted, first, that 

 there are even more abundant instances of diseased predispositions 

 breeding true, and second, that they bear out what has been already 

 emphasised, that in most cases what is inherited is rather an abnormal 

 metabolism than a specific disease. 



It is doubtful whether we are warranted in speaking of the " trans- 

 mutation of disease," for this phrase seems to suggest that a par- 

 ticular kind of process may change inhereditary transport into another 



