XXII. 



THE FEMALE GENITAL TRACT. 



rilHE female genital organs are: first, the ovaries, whose 

 A office is to produce the essential principle of reproduction 

 *. 6., the ovum 5 second, the uterus, to retain the fructified ovum 

 during the period of development 5 and third, the vagina, to 

 receive the seminal fluid of the male for fructification. The 

 o$gan, upon which reproduction mainly depends, is the ovum. 

 The mature human ovum is a globular vesicle of an average 

 diameter of 0.200 mm., inclosed by a cuticular sheath the zona 

 pellucida in which delicate radiating stria tions are seen. In the 

 ova of many animals the cuticle is known to be perforated by an 

 opening the micropyle to admit the entrance of the spermato- 

 zoids. The ovum contains granules which are partly minute, 

 partly coarse, representing the yolk, and also an eccentrically 

 situated, nucleus-like formation the vesicula germinativa the 

 bioplasson of which is distinctly reticular, holding in its center a 

 somewhat coarser granule the macula germinativa. 



The matured ovum is discharged from the ovary a few days before the 

 beginning of menstruation. It is carried by the Fallopian tube into the cavity 

 of the uterus, and in any locality, after leaving the ovarian follicle, may be 

 reached by the spermatozoids. The number of the spermatozoids which 

 penetrate the ovum is known to vary greatly, although, perhaps, a single 

 spermatozoid is sufficient for the impregnation of the ovum. As regards the 

 determination of the sex, all observers since Aristotle's time point toward the 

 fact that the sex of the future being is determined in the moment when 

 impregnation takes place. Careful observations of stock-farmers and of 

 physicians in lying-in hospitals have settled the fact that, when coition takes 

 place shortly before the appearance of menstruation, or in animals at the begin- 



