GENERATIYE ORGANS OF VERTEBRATA. 617 



The cornua of the uterus, and the common uterus itself^ vary very 

 greatly iu length ; so, too, does tlie vagina, the mucous membrane 

 of which may be variously modified. In many Rodents (Lagostomus) 

 a certain portion retains its original double nature. Its opening 

 into the urogenital sinus is sometimes distinguisbed by a temporary 

 fold of mucous membrane, which is known as the hymen. This has 

 been observed in the Ruminantia, Carnivora, etc. ; but it is in the 

 Sirni^ only that it has the same relations as in Man. The primitive 

 Mullerian duct, which only served for the passage of the generative 

 products, is therefore differentiated into three parts, owing to the 

 great physiological changes that happen to it ; and of these parts the 

 first, or Fallopian tube, alone retains its primitive relations. 



The ovaries, which are generally small, vary greatly according 

 to the relation that obtains between the follicles and the stroma of 

 the ovary. In a large number of Mammals they are racemose in 

 form. They seldom retain their primitive position, and generally 

 travel towards the pelvic basin, or, with their oviducts, are com- 

 pletely enclosed in it. They are always in close relation to the oviduct, 

 or rather to its infundibular coelomic mouth, for a process of the 

 margin of the ostium extends to the ovary. The mesenteric folds 

 (ligamenta uteri lata), which support the ovaries and oviducts, not 

 unfrequently unite with the pouch that encloses the ovary to form 

 the mouth of the oviduct (as in the Carnivora), 



Remnants of the primitive kidneys and their ducts, which are 

 enclosed with them in the genital chord, are retained at the sides 

 of the uterus, or in the folds of the peritoneum, which connect the 

 ovaries with the uterus. The so-called canals of G-artner are 

 formed by remnants of the archinephric ducts, which accompany 

 the uteri in Echidna, and open into the urogenital sinus ; in other 

 forms, portions only of these canals persist. A rudiment of the 

 primitive kidney, which is placed near the ovaries, is known as the 

 parovarium. 



§ 455. 



In the male generative apparatus of the Mammalia the 

 testes have, at first, the same position as the ovaries — that is, they 

 are placed at the inner edge of the primitive kidneys. A chord 

 extends from the archinephric duct to the inguinal region of the 

 abdominal wall (h). The primitive kidneys are partly united with 

 the testes, and there fox'm the parorchids (epididymes). As in 

 the female, the archinephric duct unites with the Mullerian duct 

 to form a genital chord, which passes to the urogenital sinus, 

 developed from the lowest portion of the allantois. It forms 

 the vas deferens ; the Mullerian duct is atrophied, its terminal 

 portion only being, as a rule, converted into a permanent organ, 

 corresponding to a sinus genitalis, the so-called uterus masculinus ; 

 this generally opens into the urogenital canal between the orifices 

 of the seminal ducts. 



