TEE P(ETUS. 1051 



Wolffian body by serous folds, and is formed by a mass of young cells sustained 

 by an enveloping membrane. 



The development of this gland is accompanied by the formation of the 

 genital or JfiWpr's diui, which is seen to the inside, and in front of, the Wolffian 

 duct. Midler's duct is at first a solid cellular column, which afterwards becomes 

 a canal ; it terminates above in a blind pouch, and opens, below, into the bladder, 

 near the Wolffian duct, which is formed at the same time. 



The stroma of the genital glands in the two sexes, is the seat of a differentia- 

 tion that gives rise to a system of reticulated solid cords, called the sexual 

 cords. Its surface is covered by an epithelium, which is continuous with that 

 of the peritoneum, but so specialized here as to merit the name of gerni- 

 epithelium. 



The sexual specialization is produced in the following manner : — ^ 



a. In the male, by the evolution of the sexual cords, or tubal i seminiferi. 

 The testicle is completed by the annexation of the anterior region of the 



Wolffian body, which forms the head {globus major) of the epididymis, while 

 the tail (or globus minor), vas deferens^ anc' cjaculatorg dart, are derived from 

 the Wolffian duct. Lastly, the res ir idee seminales and the origin of the urethra 

 are formed by the posterior extremity of Miiller's ducts, which join and open 

 into the uro-genital sinus, as the very short canal is named which communicates 

 between the bladder and cloaca. 



The developed testicle remains in the abdominal cavity, or descends through 

 the inguinal canal into the scrotum. The mechanism of this descent has been 

 already explained. 



(It may be necessary here to state that, in the Equine species, the testicles 

 do not usually descend into the scrotum until some time after birth — about six 

 months ; while in other animals they reach tliat sac during fcetal life. In the 

 Bovine species, the testes are in the ccrotum about the twentieth week of gesta- 

 tion, and in the Sheep and Goat about the fifteenth week ; indeed, it has been 

 observed that in all Ruminants their descent is effected before the skin is covered 

 with hair. In the Carnivora, they are usually in the scrotum a few da}s before 

 birth.) 



b. In the female, the sexual specialization is produced by a process of the 

 germ-epithelium, which results in the establishment of an ovigenous layer. The 

 F(fUo/)ian tube and its pavilion are formed by the anterior part of ]\Iiiller's duct, 

 the extremity of which shows a small linear orifice. The iderus and vagina arise 

 from the posterior part of Miiller's ducts. These lie beside each other, and 

 end by joining behind to constitute a single canal : the two divergent portions of 

 these canals comprised between the point of fusion and the Fallopian tubes form 

 the uterine cornua. 



The uterus and vagina are at first placed end to end, without any apparent 



' At tlie same time that the sexual specialization cif the genital gland is affirmed in the 

 ovary und testicles, the glands themselves affurd exact evidence of the opposed sexualities. In 

 the testicles, the germ-epitlielium is the seat of an evolution that gives rise to the primordial 

 ova which Laulanie has observed in the foetus of the Cat, measuring from "7 to -12 lu. In ihe 

 same animal species, this author has noted — with regard to the fcetal ovary — the connections 

 between the primitive sexual cords and the tubes of the Wolffian body, establishing the 

 homology of the first tubuli seminiferi. A demonstration has therefore been given for the first 

 time, of a real organic hermaphrodism of the sexual glands, and from this arises the interesting 

 notion that the sexuality of the individaal has been preceded by a period of indiflference and 

 a period of bisexuality. 



