116 DEVELOPMENT OF THE URINARY AND GENERATIVE ORGANS-. 



wards, a series of transversely coursing tubes becomes developed in the intermediate 

 cell-mass. These tubes are connected for a time .with other involutions of the 

 peritoneal epithelium (fig. 141), but subsequently lose their connection with that 



ov 



s.t 



Fig. 138. DIAGRAMS OP THE ARRANGEMENT OF THE URINARY AND GENITAL ORGANS IN ELASMOBRANCHS, 



(Balfour.) 



A. DIAGRAM OF THE PRIMITIVE CONDITION OF THE KIDNEY IN AN ELASMOBRANCH EMBRYO. 



pd, segmental duct ; opening at o, into the body cavity and at its other extremity into the cloaca \ 

 x, line of separation between the Wolffian duct above and the Miillerian duct below ; st, segmental tubes, 

 opening at one end into the body cavity and at the other into the segmental duct. 



13. DIAGRAM OF THE ARRANGEMENT OF THE URINO-GENITAL ORGANS IN AN ADULT FEMALE 



ELASMOBRANCH. 



m.d, Mullerian duct ; ic.d, Wolffian duct : s. t, segmental tubes ; five of them are represented with 

 openings into the body cavity, and five posteriorly correspond to the metanephros ; or, the ovary ; d, 

 ureter. 



C. DIAGRAM OF THE ARRANGEMENT OF THE URINO-GENITAL ORGANS IN AN ADULT MALE ELASMOBRANCH. 



m.d, rudiment of Mullerian duct ; w. d, Wolffian duct, serving at vd as vas deferens ; s. t, segmental 

 tubes, two represented with openings into the body cavity ; d, ureter ; t, testis ; nt, canal at the base 

 of the testis ; V.E, vas efferentia ; Ic, longitudinal canal of the Wolffian body. 



epithelium, and acquiring glomeruli at one part, at another part open into the 

 AYolffian duct. They form the mid-kidney, Wolffian 'bodg or mesonephros, which 



