FECUNDATION. 797 



tion, would be of great interest and might appropriately be discussed in a 

 work upon physiology ; but although the facts of hereditary influence, as 

 regards the inheritance both of physiological and morbid attributes and 

 tendencies, the influence of the maternal mind upon the development of the 

 fostus, the effects of previous pregnancies, etc., can not be doubted, their con- 

 sideration would involve little more than a mere enumeration of remarkable 

 phenomena. 



The first question which naturally arises relates to the conditions which 

 determine the sex of the offspring. Statistics show clearly enough the pro- 

 portions between male and female births ; but nothing has ever been done in 

 the way of procreating male or female children at will. According to Longet 

 the proportion of male to female births is about 104 to 105, these figures pre- 

 senting certain modifications under varying conditions of climate, season, 

 nutrition etc. It has been shown, by very extensive observations upon cer- 

 tain of the inferior animals, that the preponderance of sex in births bears a 

 certain degree of relation to the vigor and age of the parents ; and that old 

 and feeble females fecundated by young and vigorous males produce a greater 

 number of males, and vice versd ; but no exact laws of this kind have been 

 found applicable to the human subject. The idea that one testicle produces 

 males, and the other, females, or that the two ovaries have distinct offices in 

 this regard, has no foundation in fact ; for men with one testicle or females 

 with a single ovary produce offspring of both sexes. 



No definite rule can be laid down with regard to the transmission 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 ; sometimes 

 there appears to be no such relation; and occasionally peculiarities are 

 observed, derived apparently from grandparents. This is true with regard 

 to pathological as well as physiological peculiarities, as in the inherited 

 tendencies to certain diseases, malformations etc. 



A peculiar and, it seems to be, an inexplicable fact is that previous preg- 

 nancies have an influence upon offspring. This is well known to breeders of 

 animals. If pure-blooded mares or bitches have been once covered by an 

 inferior male, in subsequent fecundations the young are likely to partake of 

 the character of the first male, even if they be afterward bred with males of 

 unimpeachable pedigree. What the mechanism of the influence of the first 

 conception is, it is impossible to say ; but the fact is incontestable. The same 

 influence is observed in the human subject. A woman may have, by a second 

 husband, children who resemble a former husband, and this is particularly 

 well marked in certain instances by the color of the hair and eyes. A white 

 woman who has had children by a negro may subsequently bear children to 

 a white man, these children presenting some of the unmistakable peculiarities 

 of the negro race. 



Superfecundation of course does not come in the category of influences 

 just mentioned. It is not infrequent to observe twins, when two males have 

 had access to the female, which are entirely distinct from each other in their 



52 



