INHERITANCE OF MENTAL DEFECTS AND DISEASE 65 



produce more serious degeneracy and terminate in the idiocy or 

 imbecility of those who form the last link in the chain of hered- 

 itary transmission." 



Dr. Moreau, a prominent member of the same school, tells 

 us that "it is not in the identity of functions, or of organic or 

 intellectual facts that we must seek the application of the law of 

 heredity, but at the very fountain head of the organism, in its 

 inmost constitution. A family whose head has died insane or 

 epileptic does not of necessity consist of lunatics and epileptics, 

 but the children may be idiotic, paralytic, or scrofulous. What 

 the parents transmit to the children is not insanity, but a vicious 

 constitution which will manifest itself under various forms in 

 epilepsy, hysteria, scrofula, rickets, etc. This is what is to be 

 understood by hereditary transmission." 



The same idea is emphasized by Fere in La Famille Neuro- 

 pathique. "Le plus souvent, la maladie qui se transmet se trans- 

 forme; c'est ainsi qu'on voit succeder la manie, la melancolie, 

 I'imbecillite, I'idiotie." The lack of fidelity which characterizes 

 the transmission of defect is regarded as a result of the "dissolu- 

 tion of heredity" occasioned by a lack of developmental energy 

 (defaut d'energie embryogenique) . "La degredation de la puis- 

 sance embryogenique, demontree par la frequence de malfor- 

 mations varices, et en fin de compte par la sterilite dans les races 

 degenerees permet de comprendre a la fois I'heredite morbide 

 dissemblable, et I'heredite morbide collaterale." But, as Fere 

 hastens to add, the sequences of degenerative changes do not 

 follow without rhyme or reason. There is a more or less definite 

 grouping of symptoms constituting a family of related defects. 

 "La degenerescence a ses lois comme revolution normale; quelle 

 que soit sa cause, elle se manifeste sous un petit nombre de formes 

 communes." 



If degeneration is due to a general defect of developmental 

 energy or the presence of factors which exercise an injurious 

 influence upon the evolution of the embryo, its protean manifes- 

 tations need not surprise us. One of the most conspicuous fea- 

 tures of the results of experimentation upon the effects of external 



