1. FATTY ACID OCCURRENCE AND DISTRIBUTION
33
valeric acid is present only in small amounts (1.2%), contains much less
C 20 and C 22 unsaturated acids than the blubber of the adult (168), as
shown in Table VII.
4. Fats of Freshwater Fishes
The fats of freshwater species generally conform to the average
freshwater type described by Lovern (169). The flesh fats of the sea
trout and the brown trout, which we now regard as migratory and nonmigratory forms of the same species (Salmo trutta), show, respectively,
the marine and freshwater types of fatty acid composition. Although
the sturgeon (Acipenser sturio) fats examined by Lovern (170) were
from a North Sea specimen, it was believed that the freshwater type of
fatty acid composition found was associated with feeding in fresh water.
Most of the fats of freshwater species examined have been taken from
the body, and the concept of an average freshwater type is based on
British species. Pathak and Ojha (171) found that the body fats of
Indian freshwater species were high in y^i8 unsaturated acids but low
in C 20 and C 22 unsaturated acids, in accordance with the observations
made on specimens taken in Great Britain. However, as compared with
Lovern's average freshwater type, the Indian species have a much
higher content (27-44%) of saturated acids, chiefly palmitic acid, but
a lower content of hexadecenoic acid. These investigators suggest that
biohydrogenation may occur to a greater degree in the fats of Indian
freshwater fishes from tropical waters than in the colder waters of
Britain. It was also shown that visceral oils, as compared with the
body oils, contained lower proportions of C 22 unsaturated acids. On the
other hand, the liver oil from an Indian species of freshwater fish
(Wallago attu) examined by Pathak and Agarwal (172) showed 19.1%
C 22 and was generally similar in composition to that of marine species.
Of the warm-blooded animals inhabiting fresh water, Meara and
Weerakoon (173) found that the depot fats of the duckbill platypus
(Omithorhynchus anatinus)—an egg-laying mammal—possess the freshwater type of fat.
C. FATS OF TERRESTRIAL ANIMALS
Although only a small part of the total number of species has been
examined, particularly among the invertebrates, the data show that the
terrestrial animals have depot fats distinct from those of aquatic animals in their relative lack of C 20 and C 22 highly unsaturated acids. The
depot fats of amphibia and of reptiles are intermediate in this respect
between those of more highly evolved land animals and those of
33
valeric acid is present only in small amounts (1.2%), contains much less
C 20 and C 22 unsaturated acids than the blubber of the adult (168), as
shown in Table VII.
4. Fats of Freshwater Fishes
The fats of freshwater species generally conform to the average
freshwater type described by Lovern (169). The flesh fats of the sea
trout and the brown trout, which we now regard as migratory and nonmigratory forms of the same species (Salmo trutta), show, respectively,
the marine and freshwater types of fatty acid composition. Although
the sturgeon (Acipenser sturio) fats examined by Lovern (170) were
from a North Sea specimen, it was believed that the freshwater type of
fatty acid composition found was associated with feeding in fresh water.
Most of the fats of freshwater species examined have been taken from
the body, and the concept of an average freshwater type is based on
British species. Pathak and Ojha (171) found that the body fats of
Indian freshwater species were high in y^i8 unsaturated acids but low
in C 20 and C 22 unsaturated acids, in accordance with the observations
made on specimens taken in Great Britain. However, as compared with
Lovern's average freshwater type, the Indian species have a much
higher content (27-44%) of saturated acids, chiefly palmitic acid, but
a lower content of hexadecenoic acid. These investigators suggest that
biohydrogenation may occur to a greater degree in the fats of Indian
freshwater fishes from tropical waters than in the colder waters of
Britain. It was also shown that visceral oils, as compared with the
body oils, contained lower proportions of C 22 unsaturated acids. On the
other hand, the liver oil from an Indian species of freshwater fish
(Wallago attu) examined by Pathak and Agarwal (172) showed 19.1%
C 22 and was generally similar in composition to that of marine species.
Of the warm-blooded animals inhabiting fresh water, Meara and
Weerakoon (173) found that the depot fats of the duckbill platypus
(Omithorhynchus anatinus)—an egg-laying mammal—possess the freshwater type of fat.
C. FATS OF TERRESTRIAL ANIMALS
Although only a small part of the total number of species has been
examined, particularly among the invertebrates, the data show that the
terrestrial animals have depot fats distinct from those of aquatic animals in their relative lack of C 20 and C 22 highly unsaturated acids. The
depot fats of amphibia and of reptiles are intermediate in this respect
between those of more highly evolved land animals and those of