34.6 GENERATION. 



Two ideas with regard to the determination of sex in the 

 foetus have obtained at different times. One of these is that 

 the sex is dependent upon nutritive or other conditions sub- 

 sequent to fecundation, and the other, that the sex is deter- 

 mined at the time of union of the male with the female 

 element. Of these two opinions, the weight of evidence 

 appears to be in favor of the latter. Aside from facts in 

 comparative physiology, it is pretty certain that several sper- 

 matozoids are necessary for the fecundation of a single ovum. 

 It may be that, when just enough of the male element unites 

 with the ovum to secure fecundation, or when it might be 

 said that the female element predominates, the foetus is a 

 female, and when a greater number of spermatozoids unite 

 with the vitellus, the male sex is determined. Such an idea, 

 however, is purely theoretical ; and the question of the deter- 

 mination of sex presents thus far hardly the shadow of a 

 satisfactory explanation. 



~No definite rule can be laid down with regard to the trans- 

 mission of mental or physical peculiarities to offspring. 

 Sometimes the progeny assumes more the character of the 

 male than of the female parent, and sometimes the reverse is 

 the case, without any reference to the sex of the child ; some- 

 times there appears to be no such relation ; and occasionally 

 we note peculiarities derived apparently from grandparents. 

 This is true with regard to pathological as well as physio- 

 logical peculiarities, as in inherited tendencies to certain dis- 

 eases, malformations, etc. 



A peculiar, and, it seems to be, an inexplicable fact is 

 that previous pregnancies have an influence upon offspring. 

 This is well known to breeders of animals. If a pure-blooded 

 mare or bitch have been once covered by an inferior male, 



lately been reported by Prof. Marzolo, of Padua. In a patient, thirty-four years 

 of age, the left ovary was removed for cystic tumor. The woman recovered 

 from the operation, and became pregnant about a year after. She was delivered 

 at full term of twins, a male and a female, and both of the children did well. 

 (Gazette medicale de Paris, 1873, No. 44, p. 582.) 



