AMPHIBIA 



289 



ventral surface is flatter than the dorsal. The orange-colored ad- 

 renal body, on the ventral surface, is a gland of internal secretion. 

 (See page 286.) The kidneys are made up of coiled uriniferous 

 tubules with a knot of blood vessels, the glomerulus^ at one end. 



The Wolffian duct is the sperm- 

 duct in the male and the ureter 

 In the female. The Miillerian 

 duct is the oviduct in the female 

 and rudimentary in the male of 

 Rana pipiens. It is absent in the 

 bull frog. The kidneys of the 

 male frog are closely related to the 

 sexual organs. (Figures 153 and 



154-) 



The vasa eferentia are ducts 

 carrying spermatozoa from the 

 testes, passing into the substance 

 of kidneys and through the kidney 

 to the ureter which acts as a vas 

 deferens also and is called Ley dig s 

 duct. 



The kidney receives blood 

 from two sources, the renal ar- 

 teries from the aorta and the renal 

 portal veins which bring venous 

 blood to be purified. The kidney 

 secretes urea (NH2CO3) and Na, 

 K, Ca, and Mg phosphates and 

 chlorides. 



The urinary bladder is a bilobed 

 sac attached to the ventral side of 

 the cloaca below the openings of 

 t\xQ ureters. The bladder collects Fi^- ^S^- Ventral view of the nervous 

 11, -11 system or frog. (After Woodruff, Foun- 



urme when the cloaca is closed. , ,. / d- 7 c -c ^ /- 



dations of Biology, from ncker. Lourtesy 



Nervous System.''— i:\i^ brain of The Macmillan Co.) 

 (Figure 155, A^ B, andC) consists 



of small olfactory lobes at the anterior end of the two elongated 

 cerebral hemispheres; two large optic lobes^ a diencephalon with the 

 vestigial pineal stalk attached, a narrow cerebellum situated just 



^ Strong, O. S. 1895. Cranial nerves of amphibia. Jour. Morphol., vol. 10. 



