282 SUMMARY OF CURRENT RESEARCHES RELATING TO 



of the varioas glandular structures in the different parts of the oviduct. 

 The funnel glands perhaps secrete the chalaziferous layer — a very thin 

 layer of dense albuminous substance next the yolk. The two sets of 

 glands in the albumen-secreting portion form the dense albumen. 

 The isthmus forms the shell-membrane, but also some albumen. It has 

 been shown by Pearl and Curtis that the uterus not only forms the 

 shell. l3ut secretes thin albumen which must pass through the shell and 

 the membrane by osmosis. It is probable that throughout the oviduct, 

 with the exception of the vagina, the unicellular glands are concerned 

 in the production of a fluid or thin albumen. On this view, the 

 characteristic difference of each region of the oviduct anterior to the 

 vagina, is due to the activity of the tubular glands which may secrete the 

 chalaziferous layer, the dense albumen, and the shell-membrane. In the 

 vagina the unicellular glands are perhaps concerned in secreting the 

 delicate outer shell cuticle and the colouring matter of the shell. 



Fatty Bodies of Batrachians.* — Pierre von Kennel finds that these 

 ^^'ell-known liodies have a double role. They should be called adipo- 

 lymphoid. In Anura, they are digitate ; in Gymnophiona and Urodela 

 they are entire or lobed. They are relatively more developed in Gymno- 

 phiona than in Urodela, and in Urodela than in Anura. There has been 

 a shunting forAvard. 



In origin they are distinct from the gonads. Their vascular system 

 has no true capillaries. The circulation is lacunar. There is a lym- 

 phatic system. They have not superficial ciha, unless as a transitory 

 differentiation. 



Their structure is serous. They are specializations of the peri- 

 toneum. Their two functions are storage of fat and lympho-poiesis. 

 The fat is at a maximum at the beginning of winter, at a minimum just 

 after reproduction. The removal of the organs does not hinder pairing 

 or oviposition. The organs may be regenerated at other parts of the 

 peritoneum. They are homologues of the lymphoid organs of bony 

 fishes. 



Teeth of Lumpsucker. — Bruno Schmidt gives an account of the 

 " homodont " dentition of Cydopterus lumjms. Before l)irth, the teeth 

 belong to the placoid type, ectoderm and mesoderm l)eing simultaneously 

 modified. After birth the teeth are formed deep in the mesoderm, each 

 in association with an epithelial papilla. The replacement is horizontal, 

 the oldest teeth l)eing at the outer margin of the jaw. Each tooth arises 

 and develops independently. 



The teeth consist of (1) enamel meml)rane, a very delicate outer 

 pellicle ; (2) enamel, forming an apical cap ; (3) vitrodentiue, forming 

 an envelope beloAv the enamel or the enamel membrane ; (4) dentine, 

 perforated l)y interglobular spaces and passing externally into a pris- 

 matic dentine layer ; and (5) normal dentine with dentine tubules 

 which contain Tomes's fibres. The first teeth are, in origin, quite like 

 the placoid scales, and in the lumpsucker there can be no doubt as to 

 the homology between teeth and scales. 



* Ann. Sci. Nat. (Zool.) xvii. (1913) pp. 219-54 (17 figs.). 



t Jen. Zeitschr. Naturw., xlix. (1913) pp. 312-72 (3 pis. and 23 figs.). 



