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704 URINE.
although, as Salaskin and Zaleski and Lang have shown, after the
extirpation of the liver, and increase in the formation of lactic acid pri-
marily occurs, and this causes an increase in the elimination of ammonia
(neutralization ammonia). The direct proof for the uric-acid formation
from ammonia and lactic acid in the liver of birds has been given by
Kowalewsky and Salaskin1
by means of blood-transfusion experiments
on geese with extirpated livers. They observed a relatively abundant
formation of uric acid after the addition of ammonium lactate and a
still greater formation after arginine. They not only consider ammonium
lactate but also amino-acids as substances from which the uric acid can
be produced in the liver by synthesis. That these, for example, leucine,
glycocoll, and aspartic acid, increase the elimination of uric acid in
birds was first shown by v. Knieriem.2
The possibility of a formation of uric acid from lactic acid has been
shown in another manner by Wiener,3
namely, by feeding birds with
urea and lactic acid and different non-nitrogenous substances, oxy-,
keto-, and dibasic acids of the aliphatic series. The dibasic acids, with a
chain of 3 carbon atoms or their ureides, showed themselves most active
as uric-acid formers, and Wiener is therefore of the opinion that the
active substances must first be converted into dibasic acids. By the
attachment of a urea residue the corresponding ureide is produced,
according to Wiener, and from this the uric acid is derived by the attach-
ment of a second urea residue.
Among the substances tested, only tartronic acid and its ureide, dialuric acid,
have shown themselves active in the experiments with the isolated organs, and
Wiener therefore also considers that the other acids must be first converted into
tartronic acid by oxidation or reduction. From lactic acid, CH3 .CH(OH).COOH,
we first obtain tartronic acid, COOH.CH(OH).COOH, which by the attachment
/NH—CO\
of a urea residue forms dialuric acid, CO\ /CHOH, and from this, by
\NH—CCK
the attachment of a second urea residue, uric acid is formed.
Recently Izar 4
has shown on perfusing blood containing urea and
dialuric acid through the liver of a dog and at the same time saturating
the blood with carbon dioxide, that an abundant formation of uric acid
occurred, and that a combined action between an enzyme occurring
1
v. Schroder, Zeitschr. f. physiol. Chem., 2; Meyer and Jaffa, Ber. d. f. Chem.
Gesellsch., 10; Minkowski, Arch. f. exp. Path. u. Pharm., 21 and 31; Salaskin and
Zaleski, Zeitschr. f. physiol. Chem., 29; Lang, ibid., 32; Kowalewsky and Salaskin,
ibid., 33.
2
Zeitschr. f. Biologic, 13.
’ Hofmeistcr’s Beitrage, 2. See also Arch. f. exp. Path. u. Pharm., 42, and Ergeb-
nissc fi. Physiol., 1, Abt. 1, 1902.
4
Zeitschr. f. physiol. Chem., 73, see also ibid., 65.
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