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either intensified by descent, or modified by age, sex, or 

 accessory circumstances. In speaking of diseases as heredi- 

 tary, we do not mean that the diseases themselves occurring 

 either in ancestors or parents are actually transmitted to 

 their offspring (who under those circumstances would be 

 born with them), but what is really meant is that a certain 

 organic constitution is inherited by the children, which 

 " being likely to undergo that pathological development in 

 the ordinary circumstances of life, is therefore described as 

 a constitutional predisposition or tendency to disease. We 

 do not in the least know what is the intimate nature of the 

 predisposition, but we know that it may be greater or less in 

 different persons, and that it is thought to be so great in the 

 cases of such diseases as epilepsy, phthisis, and insanity, 

 and so likely to be transmitted to children as to be a serious 

 objection, if not an actual bar, to marriage." 1 At the same 

 time it should be remembered that the inheritance of a 

 disease-tendency, however likely, is not invariable ; for, as 

 Dr. Maudsley says, " One child may have it and another be 

 free from it. It is a very rare thing for all the children of 

 an insane parent to become insane ; indeed, it seems some- 

 times as if the child which falls a victim drains off the taint 

 for that generation, like a sort of scape-goat sent out into the 

 wilderness, so that the other children escape. Nay, more, 

 it sometimes happens that one child, aided by propitious 

 surroundings, collects, concentrates, and develops into some 

 form of genius the erratic forces which carry another child, 

 not so favoured by its circumstances, into the vagaries of 

 insanity. In like manner, it is not by any means certain 

 that all the children of a phthisical parent will have phthisis. 

 And, as regards epilepsy, although it runs in families in a 



1 Dr. Maudsley. 



