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562 TISSUES OF THE CONNECTIVE SUBSTANCE.
tions, which were continued for a series of years, were subject to such
great defects that they are not conclusive as to the formation of fat
from proteins. He especially emphasizes the fact that these investigators
started from a wrong assumption as to the elementary composition of
the meat, and that the quantity of nitrogen assumed by them was too
low and the quantity of carbon too high. The relation of nitrogen to
carbon in meat poor in fat was assumed by Voit to be as 1:3.68, while
according to Pfluger it is 1:3.22 for fat-free meat after deducting the
glycogen, and according to Rubner 1:3.28 without deducting the gly-
cogen. On recalculation of the figures, using these coefficients, Pfluger
has arrived at the conclusion that the assumption as to the formation
of fat from proteins finds no support in these experiments.
In opposition to these objections, E. Voit and M. Cremer have made
new feeding experiments, to show the formation of fat from proteins,
but the proof of these recent investigations has been disputed by Pfluger.
On feeding a dog on meat poor in fat (containing a known quantity of
ether extractives, glycogen, nitrogen, water, and ash), Kumagawa 1
could not prove the formation of fat from protein. According to him
the animal body under normal conditions has not the power of forming
fat from protein.
Several French investigators, especially Chauveau, Gautier, and
Kaufmann,2
consider the formation of fat from proteins as positively
proved. Kaufmann has recently substantiated this view by a method
which will be spoken of in detail in Chapter XVII, in which he studied
the nitrogen elimination and the respiratory gas exchange in conjunction
with the simultaneous formation of heat.
As we are agreed that carbohydrates and glycogen, as well as sugar,
can be formed from proteins, the fact cannot be denied that possibly
an indirect formation of fat from proteins, with a carbohydrate as an
intermediate step, can take place. The possibility of a direct fat for-
mation from proteins without the carbohydrate as intermediary must
also be generally admitted, although such a formation has not been
conclusively proved.
According to Chauveau and Kaufmann, in the direct formation of
fat from proteins, the fat is formed besides urea, carbon dioxide, and
water, as an intermediary product in the oxidation of the proteins, while
Gautier considers the formation of fat from proteins as a cleavage
without the taking up of oxygen. If fat is formed from protein in the
animal body, then such formation is not a splitting off of fat from the
< Rosenfeld, Fettbildung, Ergebnisse der Physiologre, 1, Abt. 1.
2
Kaufniann, Arch, de physiol., (’>) 8, where the works of Chauveau and Gautier
are cited.
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