CHAPTEE XIY. 



FECUNDATION. 



Coitus Action of the male Erection Ejaculation of semen Action of the fe- 

 male Erection of the female organs Action of the cervix and os uteri 

 during sexual excitement Entrance of spermatozoids into the uterus 

 Course of the spermatozoids through the female generative passages Du- 

 ration of vitality of spermatozoids and ova Mechanism of fecundation 

 Determination of the sex of offspring Hereditary transmission Superfe- 

 cundation Influence of the maternal mind on offspring Union of the 

 male with the female element of generation Passage of the spermatozoids 

 through the vitelliue membrane. 



As far as the male is concerned, coitus is rendered possi- 

 ble by erection of the penis. This may occur before puberty, 

 but, at this time, intercourse cannot be fruitful. As we have 

 seen in a previous chapter, coitus may be impossible in old 

 age, from absence of the power of erection ; but spermato- 

 zoids may still exist in the vesiculse seminales, and fecunda- 

 tion might occur, if the seminal fluid could be discharged in- 

 to the generative passages of the female. Coitus may take 

 place in the female before the age of puberty or after the 

 final cessation of the menses, but intercourse cannot then 

 be fruitful. There are sufficiently numerous examples of 

 conception following what would be called imperfect inter- 

 course, as in cases of unruptured hymen, deformities of 

 the male organs, etc., to show that actual penetration of 

 the male organ is not essential, and that fecundation may 

 occur, provided the seminal fluid find its way into even the 

 lower part of the vagina. Conception has also followed in- 

 tercourse, when the female has been insensible or entirely 

 passive ; but we shall only consider the physiology of com- 



