EXCRETORY ORGANS. 597 



the Elasmobrancii and Amphibian testicular network is justified in 

 that both originate as outgrowths from tlie primary Malpighian 

 bodies, and thence extend into the testis, atid come into connection 

 with the true seminiferous stroma. 



As in the lower types the semen is transported from the testicular 

 network to the Wolffian duct l)y parts of the glandular tubes of the 

 Wolffian body. In the case of Keptilia the anterior two or three seg- 

 mental tubes in the region of the testis probably have this function. 

 In the case of Mamtnalia the vasa eiferentia, i.e. the coni vasculosi, 

 appear, according to the usually accepted view, to be of this nature, 

 though Banks anil other investigators believe that they are inde- 

 pendently developed structures. Further investigations on this point 

 are required. In Birds a connection between the Wolffian body 

 and the testis appears to be established as in the other types. The 

 Wolffian duct itself becomes, in the males of all Amniota, the vas 

 deferens and the convoluted canal of the epididymis — the latter 

 structure (except the head) being entirely derived from the Wolffian 

 duct. 



In the female the Wolffian duct atrophies more or less com- 

 pletely. 



In Snakes (Braun) the posterior part remains as a functionless canal, 

 commencing at the ovary, and opening into the cloaca. In the Gecko 

 (Braun) it remains as a small canal joining the ureter ; in Blindworms a 

 considerable part of the canal is left, and in Lacerta (Braun) ouly inter- 

 rupted portions. 



In Mammalia the middle part of the duct, known as Gaertner's canal, 

 persists in the females of some monkeys, of the pig and of many rumi- 

 nants. 



The Wolffian body atrophies nearly completely in both sexes ; 

 though, as described above, part of it opposite the testis persists as 

 the head of the epididymis. The posterior part of the gland from 

 the level of the testis may be called the sexual part of the gland, 

 the anterior part forming the non-sexual part. The latter, i.e. the 

 anterior part, is first absorbed; and in some Reptilia the posterior 

 part, extending from the region of the genital glands to the per- 

 manent kidney, persists till into the second year. 



Various remnants of the Wolffian body are found in the adults of both 

 sexes in different types. The most constant of them is perhaps the part 

 in the female equivalent to the head of the epididymis and to parts 

 also of the coiled tube of the epididymis, which may be called, with Wal- 

 deyer, the epoophoron'. This is found in Reptiles, Birds and Mammals ; 

 though in a very rudimentary form in the first-named group. Remnants 

 of the anterior non-sexual part of the Wolffian bodies have been called by 

 Waldeyer parepididymis in the male, and paroophoron in the female. Such 

 remnants are not (Braun) found in Reptilia, but are stated to be found 

 in both male and female Birds, as a small organ consisting of blindly 

 ending tubes with yellow pigment. In some male Mammals (including 



1 This is also called parovarium (His), and Kosenmiiller's organ. 



