URINOGENITAL ORGANS 



365 



phores, which pass into a large vesicula seininalis at the base of 

 the vas deferens ; the Mlillerian ducts are complete in the male, 

 though small. 



Herrncqyhroditism occurs amongst Fishes. In Myxine the posterior part of 

 the goiiad usually first gives rise to spermatozoa, and subsequently the anterior 

 part to ova, so that self -fertilisation is prevented. Serranus and Chryso- 

 phrys, again, are hermaphrodite, and hermaphroditism has been occasionally 

 observed in various other Fishes (e.g., Gadus morrhua, Scomber scomber, 

 Clupea, Harengus). 



Amphibia. The paired and symmetrical gonads of Amphibians 

 are situated in about the middle of the coelome ; their 

 form is usually modified by the shape of the body. Thus in the 

 Gymnophiona the ovary has the form of a long and narrow band, 

 while the testis is made up of a long chain of small bodies united 

 together by a collecting duct (Fig. 291). Each individual portioa 



JTo 



-IfS 



FIG. 291. DIAGRAM OF A PORTION OF THE MALE GENERATIVE APPARATUS OF 



THE GYMNOPHIONA. 



Ho, Ho, testis ; Sg, collecting duct of testis ; K, K, testicular capsules ; Q, Q 

 transverse canals connecting the collecting duct with the longitudinal canal 

 (L, L) ; Q 1 , Q 1 , second series of transverse canals ; M, M, Malpighian 

 capsules ; N, JV~, kidney ; ST, nephrostome ; S t convoluted portion of urinary 

 tubule ; HS, urinogenital duct. 



of the testis of Caecilians is made up of a double row of rounded 

 capsules in which the sperm is formed, and from which it is passed 

 into a collecting duct, which perforates each portion of the organ. 

 A transverse canal is given off from the free portion of the collect- 

 ing duct lying between every pair of testis lobes ; this passes to- 



