II04 PROTEIN METABOLISM [pt. iii 



Table 147 shows clearly the passage of nitrogen from raw materials 

 into embryo and also the fact that, just as with the bird, the egg- 

 white is used up before the yolk. Nakamura estimated the non-protein 

 nitrogen in the various parts of the egg during development but it 

 did not vary much, remaining always at from 14 to 25 mgm. per cent., 

 and showing only a slight rising tendency. 



Another member of the group, Sendju, studied the behaviour of 

 the amino-acids with the following interesting results : 



it is clear that the turtle's 

 egg has only half as much tryptophane, tyrosine and lysine as the 

 hen's egg, and still less cystine and histidine. The loss during develop- 

 ment seems to bear mainly on the tryptophane, tyrosine, cystine and 

 arginine, i.e. precisely those amino-acids in which definite diminutions 

 had been found by Sendju to occur during avian ontogenesis. In both 

 the turtle and the hen, the lysine remains constant, and the purine 

 bases are synthesised although it may be questioned whether Sendju's 

 figures for the latter are not much too low. Tomita found the fol- 

 lowing distribution as between white and yolk in the turtle's egg: 



Milligrams % (fresh 

 egg) wet weight 



9-9. Protein Metabolism of Amphibian Eggs 



Faure-Fremiet & Dragoiu in their analysis of the frog's egg and 

 the hatched tadpole, observed a definite diminution of protein. The 

 figures were as follows: 



