452 THE GLANDULAR ORGANS. 



tamins. The biuret reaction was positive. For a more detailed 

 account of Levene's most interesting work, and a description of the 

 method which was employed for isolating the avivitellinic acid, I 

 must refer the reader to his article. 1 



The ovivitellin as it is obtained from the yolk contains about 25 

 per cent, of lecithin. It is soluble in dilute solutions of the neutral 

 salts, and in very dilute (1 pro mille) solutions of hydrochloric acid, 

 and the hydrates and the carbonates of the alkalies. In water it 

 is insoluble, and accordingly is precipitated from its solutions on 

 copious dilution. On prolonged contact with water its properties 

 are changed, and it is converted gradually into an albuminate-like 

 substance. Sodium chloride when added to saturation causes only 

 a partial precipitation. When slowly heated in its solutions of 

 neutral salts it coagulates between 70 and 75 C. ; when rapidly 

 heated, coagulation is retarded until 80 C. is reached. On diges- 

 tion with gastric juice ovivitellin yields a paranuclein avivitellinic 

 acid. From the ovivitellin of the eggs of the bony fishes a gluco- 

 paranuclein may be obtained. 



Elementary analysis of the ichthulin of carp eggs has given the 

 following results : C, 53.52 ; H, 7.6 ; N, 15.63 ; O, 22.19 ; S, 0.41 ; 

 P, 0.43 ; and Fe, 0.1 per cent. For the ichthulin of codfish eggs 

 Levene found C, 52.44 ; H, 7.45 ; N, 15.96 ; S, 0.92 ; P, 0.65 ; Fe 

 and O, 22.58 per cent. On treating with alkalies a substance is 

 obtained from this latter form, which is quite similar in compo- 

 sition to avivitellinic acid, as is seen from the figures: C, 32.56; 

 H, 6 ; N, 14.03 ; S, 0.146 ; P, 10.34 per cent. It is termed ich- 

 thulinic acid (see also page 461). 



ISOLATION. To isolate the ovivitellin from the yolk, it is well to 

 employ a large number of eggs. The yolks are thoroughly mixed 

 with an equal volume of a 10 per cent, solution of sodium chloride, 

 and are completely extracted with ether, by shaking, viz., until no 

 more coloring-matter can be removed, and the sodium chloride 

 solution has become perfectly transparent. This is then diluted 

 with twenty times its volume of water, and the ovivitellin thus 

 precipitated. To purify the substance further, it is dissolved re- 

 peatedly in a 10 per cent, saline solution, and reprecipitated with 

 water. It is washed finally with alcohol and ether, and dried over 

 sulphuric acid. 



The Fats. The fat of the yolk consists almost entirely of olein, 

 palmitin, and stearin. As a whole, it contains a somewhat smaller 

 amount of carbon than ordinary fat, which may be due to the pres- 

 ence of mono- and diglycerides, or to the presence of a fatty acid 

 which contains less carbon than usual. On saponification Lieber- 

 mann obtained 40 per cent, of oleic acid, 38.04 per cent, of palmitic 

 acid, and 15.21 per cent, of stearic acid. 



The lipochromes or luteins of the yolk can be isolated as follows : 

 the fats of the yolk are saponified by boiling with an alcoholic 

 1 Zeit. f. physiol. Chem., vol. xxxi. pp. 543-556. 



