52 AMPHIBIA CHAP. 



breeding season and form many convolutions. As a rule each 

 oviduct opens separately into the cloaca, but in Hyla they have 

 one unpaired opening, while in Bufo and Alytes the lower parts 

 of both oviducts are themselves confluent. 



All Amphibia possess Fat-bodies. They consist of richly 

 vascularised lymphatic tissue, the meshes of which are filled with 

 lymph-cells, globules of fat and oil. In the Apoda these bodies 

 lie laterally to the generative glands, and along the posterior half 

 of the kidneys. In the Urodela they accompany the anterior 

 half of the kidney. In the Anura they are lobate, and are 

 placed upon the anterior, end of the testes or ovaries. Their 

 exact function is still doubtful, but it is intimately connected 

 with that of the generative glands. The old notion, that 

 they are simply stores of fat for the nourishment of the animal 

 during hibernation, is quite untenable. The fat-bodies do not 

 decrease during this period, on the contrary they attain their fullest 

 size in the spring at the time of the rapidly awaking activity of 

 the reproductive organs, and they enable considerable quantities 

 of sperma and of eggs to be produced and ripened without detri- 

 ment to, or utter exhaustion of, the animals, which often spawn 

 before they have had time or opportunity to feed. After the 

 spawning season the fat-bodies have dwindled down to incon- 

 spicuous dimensions. 



Lastly, there is in some Anura, hitherto observed in Bufo only, 

 a mysterious organ, intercalated between the fat-body and the 

 testis or ovary. This is " Bidder's organ " and it seems to be a 

 rudimentary ovary, or rather that upper, anterior portion of the 

 whole organ which undergoes retrogressive metamorphosis. It 

 disappears in old female toads, but in the males it sometimes 

 assumes a size equal to, or surpassing that of the testes. The 

 males are in this respect hermaphrodite, and cases are known in 

 which parts of the generative glands have developed testes and 

 egg-bearing ovaries. 



The spermatozoa of the Apoda and Urodela have an undulat- 

 ing membrane along the tail, while the head-end is either pointed 

 or truncated. Those of Spelerpes fuscus and of Ichthyophis 

 glutinosa measure about 0'7 mm. in total length, those of the 

 other Urodela being much smaller. A peculiarity of the Urodela is 

 that their spermatozoa are massed together in or upon spermato- 

 phores, an arrangement which undoubtedly facilitates the internal 



