474 COMPARATIVE ANATOMY 



The cloaca in both sexes of Urodeles is provided with definite 

 integumentary lips, and its cavity is often subdivided by folds. In 

 the female, its side walls enclose numerous tubes, which, during the 

 breeding season, serve as receptacula seminis. 1 In the male the lips 

 and dorsal wall of the cloaca include numerous glands, amongst 

 which special pelvic and abdominal portions may be recognised, and 

 which are especially well-developed in the breeding season. These 

 serve to secrete a protective jelly-like mass around the spermatozoa, 

 thus uniting them into packets, or spermatophores. It has been 

 observed in Newts that as the spermatophores are extruded from 

 the cloaca of the male, they become taken up by the female 

 between the lips of the cloaca, so that fertilisation of the eggs 

 takes place before, and not after oviposition, as is the case in 

 Anura. 



Fat-bodies (corpora adiposa) are present in all Amphibia in 

 connection with the gonads : they are formed of adenoid tissue, 

 fat, and leucocytes, and contain numerous blood-vessels. These 

 bodies have probably an important physiological (nutritive) re- 

 lation to the gonads : after remaining for months without food, 

 throughout their winter sleep, Amphibians are able as soon as 

 spring arrives to produce thousands of offspring. 



Reptiles and Birds. The essential differences between the 

 urinogenital organs of the Anamnia and Amniota have already 

 been referred to (cf. Fig. 339). 



In the Sauropsida, as in other Vertebrates, the form of the 

 gonads is influenced by that of the body : thus in Chelonians they 

 are broad, while in Snakes and snake-like Lizards they are more 

 elongated, and as well as in other Lizards, are asymmetrical, 

 the organ of one side lying more or less in front of that of 

 the other. More room is thus obtained for the development of 

 the ovaries ; and, in cases where the eggs are very large, the 

 organs of one side tend to disappear, as in certain Elasmobranchs : 

 in Birds, for instance, the left ovary only is completely developed 

 and functional. In Reptiles the ovaries are penetrated by a 

 highly vascular network of trabeculre, in the lymph-cavities of 

 which the formation of ovarian follicles takes place. 



The oviducts (Fig. 357) possess wide, funnel-shaped, abdominal 

 apertures, and are usually much folded transversely ; the right is 

 often longer than the left. Their walls are provided with numerous 

 muscular elements and glands for the formation of the albumen 

 and egg-shell, and they increase in size in the breeding-season. 

 In Birds the right oviduct, as well as the right ovary, becomes 



more or less completely degenerated, and the left is considerablv 



11 

 coiled. 



Only slight remnants of the mesonephros and Wolffian duct 



1 In Salamandra maculata and S. atra the contained sperms may retain their 

 vitality for a year or two. 



