The kidneys consist of a large number of glomeruli, produced by the coiled segmental tubes, each of which is composed of a nephrostome or funnel opening into the body-cavity, a Malpighian body and an efferent canal. The latter combine to form the segmental duct which opens into the cloaca. The testes, composed of a large number of sperm-producing glands, are drained by transverse canals which combine into a longitudinal canal, and this again sends off numerous efferent canals which open into the efferent canals of the kidney, so that the segmental duct (Leydig's duct of many authors) conveys both sperma and urine. {49}[Illustration: FIG. 7.–Diagrammatic representation of modifications of the urino-genital ducts. 1, 2, Male and female Newt; 3, a tubule of the kidney; 4, male _Rana_; 5, male _Bufo_; 6, male _Bombinator_; 7, male _Discoglossus_; 8, male _Alytes_. _a_, Artery entering, and producing a coil in, the Malpighian body, _M_; _B_, Bidder's organ; _ef.s.c_, efferent segmental canal; _F.B_, fat-body; _gl_, glomerulus; _K_, kidney; _l.c.c_, longitudinal collecting canal; _M_, Malpighian body; _Md_, Müllerian duct; _N_, nephrostome; _O_, ovary; _Ov_, oviduct; _s.d_, segmental duct; _T_, testis; _Ur_, ureter; _V.d_, vas deferens; _V.s_, vesicula seminalis.] {50}In the female the network of transverse and longitudinal canals, which originally connect the generative glands with the kidney's efferent canals, is deduced in so far as the connection is interrupted and the vestiges of the transverse canals are no longer functional. The eggs fall into the body-cavity and are caught up by the ostium or inner abdominal opening of a special duct, the oviduct (Müllerian duct of many authors). Vestiges, more or less complete, of these oviducts persist in the males of most Amphibia. This general scheme presents some modifications in the various groups of Amphibia. The Apoda retain the most primitive conditions. The kidneys are still long and narrow, and the glomeruli are, at least in the anterior part of the organ, still strictly segmental, agreeing in number and position, each with a vertebral segment; later, the number of the glomeruli is greatly increased, and the former agreement becomes quite disturbed. The generative glands still retain their segmental arrangement, but they are restricted to a much shorter region than the kidneys. In the male Apoda a considerable portion of the cloaca can be everted by special muscles, and acts as an intromittent organ. Both sexes possess a ventral urinary bladder.