1. FATTY ACID OCCURRENCE AND DISTRIBUTION
65
decadienoic acid, neither of which is found in the fruit-coat fat. Similarly, lauric acid, the major constituent of palm kernel oil, is absent
from the fruit-coat fat.
Unfortunately there are few data permitting comparisons between
the leaf fats and seed fats of the same species. However, as earlier mentioned, the leaf fats of the Gramineae contain linolenic acid as their
main fatty acid whereas the seed fats of various species of this family
seldom contain more than 10% of this acid but consist largely of oleic
and linoleic acids (3).
The leaf fats of Brassica napus also appear to consist largely of
linolenic acid with some hexadecatrienoic acid. In the seed fats of
Brassica species generally, erucic acid is the major fatty acid constituent,
but this acid was not found in the rape leaf lipids (32). This rather
meager evidence points to the absence of correlation between the
fatty acid constituents in different parts of the plants, and would be consistent with the elaboration of specific fatty acid types in situ without
translocation to the different parts of the plant. The types and amounts
of fatty acids in different parts of the same plant provide, therefore, a
relatively unexplored field, which, on further study, could not fail to
yield interesting data.
B. VARIATIONS IN FATTY ACID COMPOSITION IN
DIFFERENT PARTS OF ANIMALS
In aquatic animals different species of fish vary in the distribution of
their fat reserves. In some the fats are diffused more or less evenly
throughout the organs and tissues whereas in others they are concentrated in the liver. Among fishes with a diffuse system of fat storage
in which different fatty depots have been examined for fatty acid
composition, are the salmon (Salmo solar) (169, 311, 312), sturgeon
(Acipenser sturio) (170), and tunny (Thunnus thynnus) (313). These
fishes, in the various depot fats, show no very marked differences in
fatty acid composition. In some marine species, such as the New Zealand
groper (Polyprion oxygeneios) (166) and the South African jacopever
(Sebastichthys capensis) (165), in which the liver is also a secondary
fat depot, the liver oil fatty acids are usually high in C i6 and Ci 8 unsaturated acids, but low in C 20 and C 22 unsaturated acids. The main
fat depots, on the other hand, exhibit the normal marine type of fatty
acid composition (see Table XXI).
In fishes in which fats are concentrated in the liver, such as the
New Zealand ling (Genypterus blacodes) (281), it was found that the
roe and visceral oils are somewhat richer in C 2 o and C 2 2 unsaturated
acids than the liver oils, but the differences are not marked. Similarly, in
65
decadienoic acid, neither of which is found in the fruit-coat fat. Similarly, lauric acid, the major constituent of palm kernel oil, is absent
from the fruit-coat fat.
Unfortunately there are few data permitting comparisons between
the leaf fats and seed fats of the same species. However, as earlier mentioned, the leaf fats of the Gramineae contain linolenic acid as their
main fatty acid whereas the seed fats of various species of this family
seldom contain more than 10% of this acid but consist largely of oleic
and linoleic acids (3).
The leaf fats of Brassica napus also appear to consist largely of
linolenic acid with some hexadecatrienoic acid. In the seed fats of
Brassica species generally, erucic acid is the major fatty acid constituent,
but this acid was not found in the rape leaf lipids (32). This rather
meager evidence points to the absence of correlation between the
fatty acid constituents in different parts of the plants, and would be consistent with the elaboration of specific fatty acid types in situ without
translocation to the different parts of the plant. The types and amounts
of fatty acids in different parts of the same plant provide, therefore, a
relatively unexplored field, which, on further study, could not fail to
yield interesting data.
B. VARIATIONS IN FATTY ACID COMPOSITION IN
DIFFERENT PARTS OF ANIMALS
In aquatic animals different species of fish vary in the distribution of
their fat reserves. In some the fats are diffused more or less evenly
throughout the organs and tissues whereas in others they are concentrated in the liver. Among fishes with a diffuse system of fat storage
in which different fatty depots have been examined for fatty acid
composition, are the salmon (Salmo solar) (169, 311, 312), sturgeon
(Acipenser sturio) (170), and tunny (Thunnus thynnus) (313). These
fishes, in the various depot fats, show no very marked differences in
fatty acid composition. In some marine species, such as the New Zealand
groper (Polyprion oxygeneios) (166) and the South African jacopever
(Sebastichthys capensis) (165), in which the liver is also a secondary
fat depot, the liver oil fatty acids are usually high in C i6 and Ci 8 unsaturated acids, but low in C 20 and C 22 unsaturated acids. The main
fat depots, on the other hand, exhibit the normal marine type of fatty
acid composition (see Table XXI).
In fishes in which fats are concentrated in the liver, such as the
New Zealand ling (Genypterus blacodes) (281), it was found that the
roe and visceral oils are somewhat richer in C 2 o and C 2 2 unsaturated
acids than the liver oils, but the differences are not marked. Similarly, in