340 



THE UNFERTILISED EGG AS A 



[PT. Ill 



phorus in sea-urchin eggs, and Needham & Needham found only 

 very little. It is interesting to note that the ratio is subject to large 

 fluctuations among the keratins of the egg-cases. As for the albumens 

 which Konig & Grossfeld isolated from the eggs of the sturgeon and 

 the cod, they seem to approach in their composition, in so far as data 

 for the hexone bases permit one to form a conclusion, the ovoal- 

 bumen in the hen's egg. The 8 per cent, of tyrosine obtained from the 

 sturgeon ovoalbumen is, however, remarkable. The mucoprotein which 

 Komori found around the eggs of the gastropod Hemifusus tuba, and 

 which he partially analysed, is not sufficiently well characterised to 

 be compared except roughly with the mucoprotein of the amphibian 

 egg-jelly. 



Table 39. 



In % total nitrogen 



Species 



Torpedo {Torpedo marmorata) 



Sturgeon 



Dogfish (Scyllium stellare) 



„ (Pristiurus melanostoma) 

 ,, (Scy Ilium caniculd) 



Hen 



Herring ... 



Sea-urchin 



Brook-trout 



Giant salamander 

 Hen 



Protein 

 Ichthulin 



Ovokeratin 



Ichthulin 



Egg-membrane 

 protein 



Mixed egg- 

 proteins (total) 



Mixed egg-pro- 

 teins (coag. only) 



Mixed egg- 

 proteins 



Vitellin (for i 



comparison) 



15-67 

 1609 

 i5-o8 

 14-33 

 14-23 

 1 6-43 

 14-09 



ipz 



8-49 



849 1-26 6o-20 



9-51 

 5-09 

 5-13 



449 

 660 

 i-8i 



0-99 

 0-56 

 0-14 

 0-24 



0-21 



63-60 

 79-66 



66-45 

 64-19 

 73-70 

 61-77 



25-10 

 27-65 

 15-78 

 28-78 

 30-75 

 2050 

 27-02 



2-40 

 2-30 

 5-04 

 2-31 

 209 

 3-55 

 2-29 



Investigator 

 and date 



Rothera (1904) 

 Buchtala (1908) 



Steudel & Takahashi 



(1923) 

 Steudel & Osato 



(1923) 

 Russo (1926) 



7-33 2-05 — 62-11 25-91 2-40 



— 284 45-70 17-30 2-64 



— — — 62-20 29-80 209 ,, 



1-82 — — 61-55 28-25 2-18 Gortner (1913) 



2-25 — 

 1-63 S-55 



53-73 29-35 1-83 



67-10 25-10 2-67 Plimmer (1908) 



The general distribution of nitrogenous substances in the eggs of 

 the lower animals is shown in Tables 40 and 41. Pigorini's investiga- 

 tion of the silkworm egg is suggestive, but his data about the 

 different protein fractions are insufficient to enable us to form any 

 judgment on their relation to those so well known in the bird's egg. 

 The very large amount of mucoprotein in the silkworm ovum is 

 certainly remarkable. In Table 41 are placed the few data which 

 we have on the relative amounts of protein and non-protein nitrogen 

 in different eggs, and the way the protein is divided between keratin, 

 albumen, and ichthulin or vitellin. Clearly enough there is great 

 variation, and a rough dichotomy into two groups, one in which the 



