SECT, i] PHYSICO-CHEMICAL SYSTEM 339 



of arginine and lysine over histidine, which is a constant feature of 

 the ichthulins, reaches greater values in the latter than in the case 

 of bird vitellin (see Table 38). Again, bird vitellin always shows 

 a notable proportion of proline and leucine, and this is also the case 

 with the vitellins of the lower animals (e.g. 10 per cent, of leucine 

 in gastropod vitellin, 19 per cent, in snake vitellin and 9 per cent, 

 in herring ichthulin), though the amount of proline is usually not so 

 great. The only instance of a real divergence between bird and other 

 vitellins would appear to be the glutamic acid content, which is 

 always high in the former, although this amino-acid is absent from 

 the latter. 



Table 38. Hexone bases of yolk-proteins. 



In gm. % original 

 In % total nitrogen protein 



Investigator 



Species Protein Hist. Arg. Lysine Hist. Arg. Lysine and date 



Herring Ichthulin 2-45 I4"50 10-07 I'^S 6-33 7-40 Steudel & Takahashi (1923) 



Egg-menibrane 3-99 14-41 7-51 2-09 6-35 5-55 Steudel & Osato (1923) 

 protein 



Hen Vitellin — — — i-go 7-46 4-81 Osborne & Jones ( 1 909) 



Herring Ichthulin 0-40 2-70 2-00 — — — Hugounenq (1904) 



(clupeovin) 



Sturgeon Ichthulin 0-47 0-97 o-oi — — — Konig & Grossfeld (1913) 



Cod Ichthulin 0-55 0-54 0-02 — — — ,, ,, 



Trout Ichthulin 0-54 0-41 o-oi — — — ,, ,, 



Gastropod Ichthulin None 3-73 0-86 — — — Komori (1926) 



Frog Vitellin 1-14 1-06 0-29 — — — Galimard (1904) 



(ranovin) 



Snake Vitellin 0-30 0-32 1-45 — — — ,, 



If now Table 39 is considered, it will be seen that variations are 

 present in the general analysis of these proteins, but that they tend 

 to cancel each other out among the groups. Thus the mono-amino- 

 acid/di-amino-acid ratio is very constant indeed in different ichthulins, 

 although Rothera himself considered that he was dealing with two 

 entirely different proteins, the vitellin of the Torpedo egg and that 

 of the sturgeon. It is unfortunate that Komori's examination of 

 gastropod vitellin was confined to the estimation of the amino-acids 

 by isolation, and did not include a van Slyke determination of the 

 relative amounts of mono-amino and di-amino acids. In contra- 

 distinction to the ichthulins, the mixed egg-proteins studied by Russo 

 and Gortner show more variation, though the former's values for two 

 sea-urchin ^gg proteins agree well with the usual vitellin figure. 

 Masing, however, was not able to find any phosphoprotein phos- 



