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FORMATION OF FATS. 503
proteins, but rather a synthesis from primarily formed cleavage products
of proteins which are poor in carbon.
The formation "/ foi from carbohydrates in the animal body’ was
first suggested by Liebig. This was opposed for some time, and until
lately it was the general opinion that a direct formation of fat from
carbohydrates not only had not been proved, but also that it was
improbable. The undoubtedly great influence of the carbohydrates on
the formation of fat as observed and proved by Liebig was explained
by the statement, that the carbohydrates were consumed instead of
the absorbed fat or that derived from the proteins, hence they have a
sparing action on the fat. By means of a series of nutrition experiments l
with different animals, with foods especially rich in carbohydrates it has
been apparently proved that a direct formation of fat from carbohydrates
does actually occur. The processes by which this formation takes place
are still unknown. As the carbohydrates do not contain such com-
plicated carbon chains as the fats, the formation of fat from carbohydrates
must consist of a synthesis, in which the group CHOH is converted into
CH2; hence a reduction must occur.
After feeding with very large quantities of carbohydrates the relation between
the inspired oxygen and the expired carbon dioxide, i.e., the respiratory quotient
—p, was found greater than 1 in certain cases (H.\xRiOTand Richet, Bleibtreu,
Kaufmaxx. Laclaxie -). This is explained by the assumption that the fat
is formed from the carbohydrate by a cleavage setting free carbon dioxide and water
without taking up oxygen. This increase in the respiratory quotient also depends
in part on the increased combustion of the carbohydrate.
When food contains an excess of fat, the superfluous amount is stored
up in the fatty tissue, and on partaking of food deficient in fat this
accumulation is quickly exhausted; and it is very probable that the
lipase is of importance here, as Loevenhart 3
has found that all over
the body where fat is deposited in large amounts lipase also occurs in
considerable amounts. There is perhaps not one of the various tissues
that decreases so much in starvation as the fatty tissue. The organism,
then, possesses in this tissue a depot where there is stored, during proper
1
Lawes and Gilbert, Phil. Transactions, 1859, part 2; Soxhlet, see Mary’s Jahresber.,
11, 51; Tscherwinsky, Landwirthsch. Versuchsstaat, 29 (cited from Maly’s Jahresber.,
13); Meissl and Stromer, Wien. Sitzungsber., 88, Abt. 3; Schultze, Maly’s
Jahresber., 11, 47; Chaniewski, Zeitschr. f. Biologie, 20; Voit and Lehmann, see C.
v. Voit, Sitzungsber, d. k. bayer. Akad. d. Wissensch., 1885; I. Munk, Virchow’s Arch.,
101; Rubner, Zeitschr. f. Biologie, 22; Lummert, Pfliiger’s Arch., 71.
2
Hanriot and Richet, Annal. de Chim. et de Phys. (6), 22; Bleibtreu, Pfliiger’s
Arch., 56 and So; Kaufmann, Arch, de Physiol. (5), 8; Laulanic, ibid., 791.
3
Amer. Journ. of Physiol., 6.
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