86 



GENERAL BIOLOGY 



its termination, in which the eggs are stored after passing through the 

 oviducts until the final egg laying. The oviducts themselves, like the 

 ovaries, vary in size at different seasons of the year. 



The gelatinous substance covering the eggs is secreted by little 

 glands in the oviducts called nidamental glands (Lat. nidus=a nest). 

 It is to be observed that the sexual organs and kidneys lie close together 

 and have a common opening, and in the male the same duct, namely, 

 the ureter, serves for an exit of both sperm and urine. A similar close 



ost.abd. 



I* 



neb.n. 



Fig. 25. The Urogenital Organs of the Frog. A, Male ; B, Female. 



ao.b., systemic arteries ; ao.c., main aortic trunk ; cav.i., vena cava inferior ; 

 cl., cloaca (dissected from the ventral side) ; coel.mes., coeliaco mesenteric artery; 

 d., large intestine; f.k., fat bodies; h.s.L, urogenital duct; h.s.l.' , entrance of uro- 

 genital duct into cloaca ; il., iliac artery ; n., kidney ; neb.n., adrenal bodies ; ost.abd., 

 funnel-shaped opening of oviduct; ov., ovary; ovid., oviduct; ovid. ', entrance of 

 oviduct into cloaca; test., testes ; ut., uterus; ves., urinary bladder; ves.' , opening 

 of bladder into cloaca; ves.sem., seminal vesicle; w., Wolfian duct; w.' , opening of 

 Wolfian ducts. (After W. Meissner.) 



relation is found in nearly all other vertebrates, and when the study of 

 embryology is taken up it will be found that the ducts and kidneys were 

 originally derived from the same region of the embryo. It is therefore 

 common to speak of the excretory and reproductive system together as 

 the urogenital system. 



THE FAT BODIES 



Directly in front of the gonads, we find a yellow organ with many 

 finger-like processes known as a fat body. It has a broader and closer 



