744 VII. LIPID DISTRIBUTION IN SPECIFIC TISSUES 



varieties. Using a new technic for the differential estimation, Welch 222 

 showed that the a-type is the more common, in the case of both lecithins 

 and cephalins. Thus, in rat brain, the phospholipids were fractionated 

 as follows: a-lecithins, 35%; ^-lecithins, 22%; a-cephalins, 20.5%; and 

 ,8-cephalins, 13%. That this distribution is not confined to the rat is 

 shown by the fact that a similar situation obtains in beef brain. In a crude 

 cephalin fraction of beef brain, 59% was accounted for as the a-isomer and 

 28% as the /3-component. Similarly, in a crude lecithin preparation, the 

 amounts of the pure a- and ^-fractions isolated were 73 and 20%, respec- 

 tively. 



In a further study of brain cephalin fractions, Burmaster 223 showed that 

 inositol phospholipid is the principal component of the /3-cephalin fraction 

 of calf brain, while phosphatidylserine and phosphatidylethanolamine are 



Table 10 



The Composition of the Fatty Acid Mixtures of the 



Ester Phosphatides of the Brain in Per Cent of Total Fatty Acids' 1 



• E. Klenk and P. Bohm, Z. physiol. Chem., 288, 98-107 (1951); E. Klenk, Der chem- 

 ische Aufbau der Nervenzellen und der Nervenfasern. Colloquium Ges. physiol. Chemie, 

 Mosbach, Baden, April 26-27 (1952). 



the main components of the a-cephalin fraction. The fatty acid composi- 

 tion of these latter two cephalin fractions has recently been proved by 

 Klenk and Bohm 224 to be quite different. These data are recorded in Table 

 10. 

 In a review article by Klenk 225 on the composition of nervous tissue, the 



222 E. A. Welch, J. Biol. Chem., 161, 65-69 (1945). 



223 C. F. Burmaster, J. Biol. Chem., 165, 577-583 (1946). 



224 E. Klenk and P. Bohm, Z. physiol. Chem., 288, 98-107 (1951). 



226 E. Klenk, Der chemische Aufbau der Nervenzellen und der Nervenfasern, Colloquium 

 Ges. physiol. Chemie, Mosbach, Baden, April 26-27 (1952). 



