Congenital Predisposition. 31 



therefore an intrauterine mode of origin, which, if strictly niter- 

 preted, is comparable to acquirement by an external influence, only 

 tliat in this instance it operates within the womb. 



It is reasonable to believe that injurious metabolic products 

 which pass through the placenta of a mother animal suffering 

 from some febrile condition (especially metabolic and nutritive 

 disturbances which react from the mother upon the embryo, 

 affecting primarily the ovum, or in the father's case affecting the 

 spermatozoon in a similar manner) occasion morbid predisposi- 

 tions, as diminished developmental energy, or perhaps a tendency 

 to excessive growth (dwarfism, fcetal chondrodystrophy, gigan- 

 tism), weak metabolic power, tendency to fatty degeneration or 

 fatty deposition {ovo genie or spermatogenie predisposition, con- 

 genital degenerative inheritance). 



According to Weissmann and Ziegler, it is quite probable that 

 often predisposition to disease and congenital pathological char- 

 acteristics are due to germinal variations; that is, that when two 

 unadapted sexual cells unite there may be developed to some de- 

 gree new and perhaps even abnormal peculiarities in the embryo 

 from the union of the two elements (amphimixis of the 

 ovum and spermatozoon). Thus healthy, strongly-constituted 

 parents may often be seen who sometimes beget offspring of 

 feeble constitution, weak-minded or of other morbid tendency. 

 The off'spring is never entirely like either parent, and the various 

 members of the same generation are never alike in bodily struc- 

 ture and character. Only in case of twins, developing from one 

 ovum or from one act of copulation, is there striking similarity of 

 the bodily features. In the mingling of the maternal and paternal 

 sexual elements two strains of hereditary tendency unite to pro- 

 duce new germinal variations. Should there be thus produced 

 new peculiarities of value to the individual, or which we care to 

 preserve, type-characteristics (precocity), these are not regarded 

 as pathological ; but it is readily conceivable that the variations 

 might but poorly fit the off'spring for life and render it but feebly 

 resistant to given pathogenic influences or show from the first 

 abnormal constitution of its tissues. In such cases is presented a 

 germinative or constitutional predisposition. 



A predisposition, no matter how developed, as well as ac- 

 quired immunity, may be transmitted to the offspring, provided 

 the individual is capable of begetting; yet not every tendency 

 toward disease and not all the resistive powers of the parent are 



