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SPECIFIC DYNAMIC ACTION. 931
On partaking of largo amounts of food, especially proteins, by car-
nivora, the digestion work in the above sense is not sufficient to account
for the increase in metabolism, and in these cases, besides this, we must
accept an increase in the chemical transformation process in the animal
body brought on by the foodstuffs in an unknown manner (specific
dynamic action of foodstuffs, according to Rubner). The only real
difference in opinion between the various experimenters consists, so far
as Hammarsten can see, in that according to the Zuntz school, normally
on supplying sufficient food it is the digestion work in the above sense
which chiefly causes the rise in metabolism after taking food, while
according to the views of Voit-Rubner, with which Heilner agrees,
it is on the contrary the specific dynamic action.
That the proteins or their cleavage products, without regard to the
digestion work, cause a rise in the metabolism seems to be generally
accepted. This rise, according to Gigon, is not proportional to the
protein supply, as on supplying quantities of protein represented by
1:2:4:3 the oxygen absorption was in the proportion 1:3:6:9 and the
carbon dioxide elimination was in the proportion 1:4:8:12. On the
introduction of glucose Gigon found, as first shown by Johansson,1
that the introduction of carbohydrate caused a proportional rise in the
carbon dioxide elimination to a maximal limit of 150 grams. The
conditions on supplying fat are harder to judge, but Gigon found no rise
in metabolism on introducing oil.
The rise in the gas exchange occurring after feeding protein and sugar
is added, according to Gigon, entirely to the basal metabolism. A
substitution in the basal metabolism of the catabolized body constituents
by the food taken does not take place according to Gigon and, as example,
the protein is not replaced from catabolism by the sugar introduced.
The isodynamic law does not apply to the metabolism occurring the
first few hours after supplying food, as shown by Johansson and Hell-
gren, and Gigon 2
believes that the foodstuffs first pass into the various
depots of the body to be later used for purposes of energy. Proteins
serve only to a slight degree to replace the catabolized body protein;
the remainder is stored up in part as glycogen and in part as fat. The
fat is deposited as such and the carbohydrates are deposited as glycogen
and fat.
As the three foodstuffs influence the metabolism in very different ways we
can, according to Gigon, speak of a specific action of the foodstuffs. This
action, according to him, is more of a material than of a dynamic kind, and the
expression, specific dynamic action, may lead to an erroneous conception.
l
Skand. Arch. f. Physiol., 21.
2
Johansson with Hellgren, Hammarsten’s Festschrift, 190C; Gigon, Skand. Arch. f.
Physiol., 21.
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