812 VII. LIPID DISTRIBUTION IN SPECIFIC TISSUES 



of the egg had little effect upon its unsaturation, although the iodine value 

 sometimes rose during the first week. 



b. Phospholipids Present in Eggs. Levene and Rolf 590 used egg yolks 

 as the source of production of lecithin. In addition to stearic, palmitic, 

 and oleic acids, small quantities of linoleic and arachidonic acid were pres- 

 ent. Yokoyama 591 was able to prepare over 6.9% of lecithin from egg yolk ; 

 it consisted of 73% of the /3-form and 27% of a-lecithin. According to this 

 investigator, a-lecithins yielded oleic, clupanodonic and "isopalmitic" 

 acids in the proportions of 72:2:26, while only oleic and "isopalmitic" 

 acids were present in the ,8-lecithins. 



Nishimoto 592 prepared cephalins from egg yolk, and noted the presence 

 of palmitic, oleic, and arachidonic acids. He reported a yield of only 

 slightly over 0.4% of cephalin from fresh egg yolks. Riemenschneider 

 et al. m confirmed the finding that only a minimal amount of cephalin was 

 present. 



Lecithin has been shown to comprise the main part of phospholipids in the 

 eggs of a variety of fowl and fishes. Masuda and Hori 593 reported that ap- 

 proximately 20% of phospholipids were present in the dried yolks of birds' 

 eggs. These workers recorded the following phospholipid : lecithin ratios 

 in various types of eggs: hen, 1.45; duck, 1.3 to 1.37; quail, 1.77 to 1.93; 

 peacock, 1.22; salmon, 1.11; prawn, 1.11; cod, 1.6; carp, 1.14; halibut, 

 1.40; herring, 2.39; shark, 1.0; and yellowtail, 2.41. The phospholipid 

 in snake eggs was reported as 0.9%, which is about one-half of the amount 

 in hens' eggs. 594 



Evidence that the lecithins and cephalins of eggs are similar to those 

 prepared from other sources is afforded by the fact that they undergo 

 similar reactions in both cases. For example, typical lysolecithin and lyso- 

 cephalin were prepared by King and Dolan, 595 by the action of rattlesnake 

 venom on egg yolk. These compounds exerted the hemolytic action which 

 would usually be expected of them. Boyd 596 found that there is a decrease 

 in choline in hens' eggs during incubation. The original quantity, which 

 amounts to 180 mg., is reduced to 50% of the original amount by the date 

 of hatching. 



690 P. A. Levene and I. P. Rolf, /. Biol. Chem., 46, 193-207 (1921); 51, 507-513 (1922). 



691 Y. Yokoyama, Proc. Imp. Acad. (Tokyo), 10, 582-585 (1934). 



692 U. Nishimoto, Proc. Imp. Acad. {Tokyo), 10, 578-581 (1934). 



693 Y. Masuda and T. Hori, /. Agr. Chem. Soc. (Japan), 13, 200-205 (1937); Chem. 

 Abst., 31, 7548 (1937). 



694 S. Fukuda, J. Biochem. (Japan), SO, 125-134 (1939). 



696 E. J. King and M. Dolan, Biochem. J., 27, 403-409 (1933). 

 696 G. S. Boyd, Biochem. J., 47, xlvii-xlviii (1950). 



