292 HEREDITY AND DISEASE 



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 easy 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 hyperaesthesia 

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



It may appear for a moment that these illustrations prove too 

 much, suggesting as they do that the inheritance of morbid 

 predispositions 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 

 " transmutation of disease," for this phrase seems to suggest 

 that a particular kind of process may change in hereditary 

 transport into another particular kind of process. It is probable 

 that some diseased conditions which get different names are 

 fundamentally the same ; it is their expression only that changes 

 in response to the conditions of nurture and environment, just 

 as a plant changes superficially in fresh soil, or just as crystals 

 of the same substance sometimes take different forms in different 

 conditions. It is generally allowed that there are groups of 

 closely related diseases. 



But the facts which are cited under the phrase " transmutation 



