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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 * 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
aminoeihyl 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 while 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.
l
Zeitschr. f. physiol. Chem., 64, 303 (1910).
2
Ibid., 73, 76 and 80.
8
Verhandl. d. physiol. Gesellsch. zu Berlin, 1890-91.
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