CHANGES IN THE OVUM. 



[07 



The organs in the female also soon indicate the sex. The urogenital 

 sinus forms the vulvular cavity or vestibule of the vagina^ so marked in the 

 lower animals. The genital tubercle becomes the clitoris — the homo- 

 logue of the penis. The cutaneous folds constitute the labia of the 

 vulva ; while the genital groove is closed at one part of its extent to 

 form \\\Q. perifieum. The mammce^ appendages of the generative organs, 

 appear in the early months of uterine life, and the teats are perforated 

 very soon. They are also seen very distinctly in the male foetus in the 

 early months. 



In certain malformations of the generative organs, more or less of 

 their primitive conditions are retained ; the most frequent of these mal- 

 formations is hermaphrodism. Examples of this are by no means un- 

 common among the lower animals, and the annexed drawing gives a 

 good example of the organs of a hermaphrodite goat, with the male parts 

 predominating. , 



s 



I 



Fig. so. 



Genital Organs of a Hermaphrodite Goat, the Male Parts predominating. 



a, a, Testas ; b, h, Combination of Epididymis with Abdominal Ends of Miillerian Ducts ; d, d, 

 Vasa Deferentia ; e, Body of Uterus and Vagina ; f, y", Uterine Cornua : ^, g, Fallopian 

 Tubes. 



SECTION IV. PERIODS OF DEVELOPMENT. 



Thus far we have traced the development of the young creature in the 

 uterus ; but as our description may appear a little confused from our 

 having described the growth of individual organs, rather than the foetus 

 as a whole, it may be advisable to adopt the plan of dividing this bodily 

 development into periods, which will also give an approximate idea of 

 its age. From conception to maturity, utero-gestation may therefore be 

 divided into seven periods or stages, as follows : — 



First Period. — Towards the second week after conception, the ovum 

 or germ has passed from the ovary into the uterus ; it is then about a 

 line in diameter (one-twelfth of an inch). 



