MORPHOLOGY OF HIGHER TYPES 



131 



OVD 



male. The cilia of the funnels of the oviduct create currents which 

 sweep the eggs and other matter into the open funnels and down 

 the oviducts. The remainder of the path to the exterior is indicated 

 by the structure and arrangement of the organs. 



In the male frog (Fig. 98) the 

 testes are connected to the kid- 

 neys by means of fine ducts, the 

 vasa efferentia. These fine ducts 

 penetrate into the kidney and 

 open into a longitudinal canal 

 {Bidder^ s canal) which is a long 

 tube running lengthwise of each 

 kidney near its median border. 

 Bidder's canal is connected with 

 the ureter by means of a series 

 of collecting tubules into which 

 the uriniferous tubules also open. 

 Spermatozoa in the frog must 

 therefore pass through the vasa 

 efferentia, Bidder's canal, the 

 collecting tubules, the ureter and 

 cloaca on their way to the ex- 

 terior. In some species of frogs, 

 the lower end of the ureter in the 

 male may be expanded into a ■^' 

 seminal vesicle in which sperms 

 are stored until they are emitted 

 at the time of breeding, 



A comparison of the repro- 

 ductive systems of the male and 

 female frogs reveals that in the 

 female the reproductive organs 

 are less intimately connected 

 with the excretory organs than 

 in the male. In reptiles and 



birds, the genital system, espe- Fig. 97. — Urinogenital system of female frog, 



„;„ii ; au 1 • • diagrammatic. A, anus; CL, cloaca; CV, post- 



ciallymthe male, is m some re- ^^^^^ ^^i^. p^ j^^^^i of oviduct; A', kidney; 



Spects more distinct from the LI, large intestine; OV, ovary; OVD, oviduct; 

 ^„^ i^ , ,1 -J. • • SI, small intestine; UB, urinary bladder; UR, 



excretory system than it is in ^,^t^,. ^rj,^ ^t^rus. 

 the Amphibia. In both these 



classes, as in the Amphibia, both excretory and genital systems dis- 

 charge into the cloaca. 



In most mammals, the two systems open to the exterior through a 

 common opening which is separate from the opening of the digestive 



