OVOVITELLIN 45 



Twenty-five yolks of eggs are carefully washed, without break- 

 ing the enveloping membrane, in a stream of water, so as to re- 

 move all traces of the whites. To the yolk is then added an equal 

 volume of 10 per cent sodium chloride solution and the solution 

 which is thus obtained is extracted from ten to twelve times 

 with twice its volume of ether in separatory funnels, extracting 

 several times after the ethereal layers fail to yield a precipitate, 

 due to the presence of lecithin, upon the addition of acetone. 

 The complete extraction occupies a period of from two to three 

 weeks. The watery layer which is finally obtained is then poured 

 into twenty volumes of distilled water, and the precipitate of 

 ovovitellin which is thus obtained is allowed to settle in tall 

 glass cylinders. The supernatant fluid is then syphoned off and 

 the precipitate redissolved in 10 per cent sodium chloride and 

 reprecipitated in the same manner. This process is repeated. 

 Finally the vitellin is dissolved in very dilute sodium hydrate 

 and the solution filtered, the filtrate being allowed to drop directly 

 into dilute acetic acid, thus reprecipitating the vitellin. This 

 precipitate is suspended in distilled water and allowed to settle 

 in tall glass cylinders. The supernatant water is then drawn off 

 and the washing with water repeated several times. The pre- 

 cipitate is then washed in 6 litres of 99.8 per cent alcohol. After 

 allowing the precipitate to settle, the supernatant alcohol is 

 syphoned off and the washing in alcohol repeated twice. The 

 vitellin is then washed twice in ether "distilled over sodium," 

 employing 6 litres each time. The thick suspension of vitellin 

 in ether finally obtained is quickly poured into a hardened filter 

 and allowed to filter and dry over sulphuric acid at 40 degrees 

 for 48 hours. The vitellin is thus obtained as a white, somewhat 

 coarse powder. 



About a gram of this ovovitellin was placed in about 30 cc. 

 of alcohol and boiled for some five minutes. About 5 cc. of the 

 alcohol, after filtration, was then tested directly for lecithin by 

 the addition of several volumes of acetone. The remainder of 

 the alcohol was evaporated down to dryness and the residue 

 (barely visible) taken up in about 10 cc. of ether. This ether 

 was then tested by the addition of several volumes of acetone. 

 Both tests proved entirely negative, not the slightest opalescence 

 being produced by the acetone; thus the ovovitellin did not con- 

 tain any lecithin. Hence the older statements to the effect that 



