The acetone-soluble lipid was obtained in the yield of 27.0g. from 1096g. of fertilized eggs (24.6g./1kg. of fresh tissue). This lipid had the following properties: acid no. 62.6; sapon. no. 177.2; iodine no. 181.4; refractive index (n20) 1.4860 and unsaponifiable matter 8.82%. The mixed fatty acids consisted of 1% myristic, 10% palmitic, 3% stearic, 1% arachidic, 7% zoomaric, 17% oleic, 13% eicosenoic, 3% docosenoic, 1% hexadecatrienoic, 13 octadecapolyenoic, 15% eicosapolyenoic, 13% docosapolyenoic, and 3% tetracosapolyenoic acids. The unsaponifiable matter consited mainly of sterols, in which no detectable amount of provitamin D was found. A discussion is presented on the changes of the lipids occurred after the fertilization of the eggs.