240 ANIMAL FATS AND PHOSPHATIDES. 



atoms of nitrogen in the molecule, and hence we differentiate between 

 monamido- (P : N = 1 : 1) , diamido- (P : N = 1 : 2) , triamido- (P : N = 1 : 3) 

 monophosphatides, etc. 



So also may the diphosphatides contain 1, 2 or 3 atoms of nitrogen 

 for every 2 atoms of phosphorus (mono- di- or triaminodiphosphatides) . 

 Phosphatides with 4 or more atoms of nitrogen for every atom of phos- 

 phorus are also claimed to occur, but these statements seem to be uncer- 

 tain. On the other hand, according to THUDICHUM, non-nitrogenous 

 phosphatides occur in the brain; but if such be true these bodies must 

 not, for the present at least, be classified as phosphatides. 



The phosphatides thus far investigated seem to be chiefly ester com- 

 binations between nitrogenous bases and fatty acid-glycerophosphoric 

 acid. According to THUDICHUM phosphatides exist which contain no 

 glycerin group and the CARNAUBON obtained by DUNHAM l from beef 

 kidneys seems to be such a phosphatide. The fatty acids occurring in 

 the phosphatides may be of different kinds. It seems that at least 

 one oleic acid radical, or another still less saturated fatty acid, occurs 

 in most of the phosphatides; still we know of phosphatides that con- 

 tain only saturated fatty acids. On this account the phosphatides may 

 be divided into saturated and unsaturated phosphatides. The unsaturated 

 add iodine, take up oxygen from the air and are auto-oxidizable and 

 are changed readily. They also give a beautiful reaction with PETTEN- 

 KOFER'S bile-acid test. 



Choline has generally been obtained as a basic constituent of the 

 phosphatides. Still other not sufficiently studied bases, have been found 

 in the plant as well as animal phosphatides and according to TRIER 2 

 aminoethyl alcohol is a probable generally distributed component of the 

 lecithins (phosphatides) . 



The phosphatides are very widely distributed in the plant as well as 

 the animal kingdom and they must undoubtedly exist as primary cell 

 constituents. We differentiate between such cell constituents which seem 

 to be absolutely necessary for the life of the cells, and those which are 

 stored up as reserve material, or are products of metabolism. The first, 

 which seem to occur in all developing cells, have been called primary 

 by KossEL 3 w r hile he calls the others secondary. The question as to 

 the division of the known cell constituents into the primary or secondary 

 groups in the above sense, cannot be answered positively in many cases. 

 In the primary group besides water and mineral bodies we include pro- 

 teins of various kinds, nucleic acids and the so-called lipoids (see below) 

 to which the phosphatides belong. 



1 Zeitschr. f. physiol. Chem., 64, 303 (1910). 



2 Ibid., 73, 76 and 80. 



3 Verhandl. d. physiol. Gesellsch. zu Berlin, 1890-91. 



