INTEGUMENT. 29 



Museum. These albinos are of a uniform yellowish 

 flesh-colour, with silvery or golden iris and cherry-red 

 pupil ; the yellow ventral blotches are preserved in 

 Bombinator. A figure of a young Alytes albino reared 

 by Lataste is given on Plate VII. Albino specimens 

 of Alytes obstetricans obtained from tadpoles by Heron- 

 Royer paired in confinement, and produced offspring 

 that were likewise affected with complete albinism. 

 But for the difficulty in getting these Batrachians to 

 breed in captivity, a race of albinos could no doubt be 

 fixed by artificial selection, as in the case of the 

 axolotl, the numerous "white" examples of which 

 are said to be all descended from an albino male 

 which paired with normal females in the Jardin des 

 Plantes at Paris some thirty years ago. 



Batrachians often "change skin," — about once a 

 month during the spring and summer. The thin, trans- 

 parent outer layer of the epidermis becomes detached 

 about the mouth, and, lubricated by an abundant secre- 

 tion of the slime glands, is pulled off by movements 

 of both fore and hind limbs, often in a single piece 

 turned inside out, especially when the operation is 

 performed in the water, and finally swallowed by its 

 owner. The casting of the epidermis on land is a 

 slower process, accompanied by ludicrous contortions ; 

 in the common toad it may last nearly an hour. 



Fig. 10. 



Piece of dorsal integument of male Bombinator pachypus ( X 8), 

 showing warts and epidermal horny asperities. 



