SECT, i] PHYSICO-CHEMICAL SYSTEM 345 



and Batoidei", and its osmotic function was well shown by the 

 reciprocal relation between salts and urea which Smith found to 

 hold in selachian tissues and fluids. 



In view of all these facts it is not surprising that Needham & Need- 

 ham in 1928 found about 5 mgm. of urea nitrogen present in the 

 Scyllium canicula egg at the beginning of development ; and 888 mgm. 

 per cent, of urea in the undeveloped Acanthias vulgaris egg. Gori, again, 

 found 7 10 mgm. in undeveloped Torpedo eggs. But since urea accumu- 

 lation is closely confined to elasmobranchs it is unlikely that the results 

 of Steudel & Takahashi and of Konig & Grossfeld can be interpreted 

 as being due to urea. 



The presence of urea has also been reported in the undeveloped 

 eggs of "ants and flies" (in small quantities) by Fosse. Further 

 details would be desirable here. 



There is reason to believe that nitrogenous substances other than 

 those already mentioned are present in certain eggs. Thus Yoshimura 

 and Poller & Linneweh isolated trimethylamine, tetramethylene- 

 diamine and choline from fresh herring eggs, and there is a certain 

 probability that fish eggs also contain betaine. As the characteristic 

 smell of fish is due to these amines and related substances, this is not 

 very surprising. Brieger is said to have found neuridine in fish eggs, 

 and Schii eking isolated spermine from echinoderm eggs in 1903. 

 Taurine and glycine were found in echinoderm eggs by Kossel & 

 Edlbacher. 



Of the manner of formation of ichthulin in the maturation of the 

 ovum we know absolutely nothing. Paton & Newbigin concluded 

 from a very few analyses that the phosphorus was brought to the 

 ovaries from the muscle of the salmon as inorganic phosphorus, but, 

 in view of what is now known about the organic phosphorus com- 

 pounds of blood, this appears rather unlikely. 



