292 PHYSIOLOGICAL CHEM1STR7. 



and of granules similar to starch (DABESTE) has not been positively 

 proved. 



Ovovitellin. This body is generally considered as a globulin, 

 but it resembles a nucleoalburnin more. The question as to what 

 relationship other proteid substances, such as the aleurone crystals 

 of certain semen, and the so-called " dotterpldttchen " in the eggs 

 of certain fishes and amphibians which are related to ovovitellm, 

 bear to this substance, is a question which requires further investi- 

 gation. 



The ovovitellin which has been prepared from the yolk of eggs 

 is not a pure albuminous body, but always contains lecithin. 

 HOPPE-SEYLEB found 25$ lecithin in vitellin and also some nuclein. 

 The lecithin may be removed by boiling alcohol, but the vitellin 

 is changed thereby and it is therefore probable that the lecithin is 

 chemically united with the vitellin (HOPPE-SEYLEB). BUNGE 

 prepared a nuclein by digesting the yolk with gastric juice, and this 

 nuclein, according to him, is of great importance in the formation 

 of the blood, and on these grounds he called it hcematogen. This 

 haematogen whose composition is as follows: 42.11, H 6.08, N 

 14.73, S 0.55, P 5.19, Fe 0.29 and 31.05$ seems to be a product 

 of the decomposition of vitellin. 



Vitellin is similar to the globulins in that it is insoluble in 

 water ; but on the contrary soluble in dilute neutral-salt solutions 

 (although the solution is not quite transparent). It is also soluble 

 in hydrochloric acid of 1 p. m. and in very dilute solutions of alka- 

 lies or alkali carbonates. It is precipitated from its salt solution 

 by diluting with water, and when allowed to stand some time iu 

 contact with water the vitellin is gradually changed, forming a sub- 

 stance more like the albuminates. The coagulation temperature 

 for the solution containing salt (NaCl) lies between -|- 70 and 75 C. 

 or, when heated very rapidly, at about + 80 C. Vitellin differs 

 from the globulins in yielding nuclein by pepsin digestion. On 

 this account vitellin, as previously stated (page 14), is considered as 

 a nucleoalbumm even though it differs from them in general by 

 the coagulation of its neutral solutions containing salt, at a tem- 

 perature below 100 C. ; also by certain solubilities and precipita- 

 tions. Because of the difficulty of removing lecithin without 

 changing the properties of vitellin it is necessary, since lecithin may 



