334 THE UNFERTILISED EGG AS A [pt. iii 



with pepsin and other methods. These with their very high 

 phosphorus content approach closely the " paranucleins " or 

 vitellic acids obtained from the vitellin of the hen's yolk by 

 Levene & Alsberg and others. Evidently there are several possible 

 stages of breakdown, for Walther's ichthulic acid only contains 2-8 per 

 cent, of phosphorus, while that of Levene has as much as 10-4. 

 Here, also, however, there are great variations; thus, while nearly 

 all the ichthulins studied have from o-6 to i -9 per cent, of phosphorus, 

 the preparation of Steudel & Takahashi from the herring's egg has 

 only 0-014 P^r cent. In the yolk of a dogfish egg, Zdarek found no 

 less than three proteins, the third of which may possibly correspond 

 with Konig & Grossfeld's albumen class. 



In 1908 Alsberg & Clark claimed that phosphorus was quite absent 

 from the principal protein of the egg of an ovoviviparous selachian, 

 Squalus acanthias, but some twenty years later I re-examined the 

 question and obtained without difficulty o-6 per cent, from selachian 

 ichthulin (derived from the same species). This yolk also contains a 

 second protein, thuichthin, corresponding closely in properties and 

 constitution with the ovolivetin of the hen studied by Kay & Marshall 

 (see Tables 10 a and 33). 



Gray has studied the properties of the ovoglobulin or ichthulin 

 of Salmo fario. If the yolks are poured into water, a dense white clot 

 is formed and the water becomes cloudy. The precipitate is soluble, 

 however, in acids, alkalies and neutral salts. When the egg-cell 

 dies, the egg becomes opaque, and this must certainly be due to the 

 precipitation of the globulin, for by placing dead white eggs in 

 normal sodium chloride solution they rapidly become clear and 

 resemble normal eggs, but regain their opacity when removed to 

 distilled water. The clearing process takes 15 minutes but the 

 precipitation takes i| hours. Evidently the dead protoplasmic 

 membrane can no longer retain in the egg the electrolytes necessary 

 for solution of the ichthulin. 



Further work on the properties of teleostean ichthulin was 

 done by Runnstrom. 1-5 parts of egg "Pressaft" having been added 

 to 1-28 parts of water and the ichthulin precipitated, the effect 

 of various ions on its solubility was tried. The anions placed them- 

 selves in the order: 



SON > I > NO, > SO. > CI > acetate. 



