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706 URINE.
by several experimenters,1
in great part destroyed and more or less com-
pletely changed into urea. As shown by Wohler and Frerichs for the
dog and by later investigators 2
also for cats, rabbits and other animals,
that allantoin is the most essential or indeed the chief decomposition
product is now considered as positively proven. In man, on the con-
trary, the conditions are different. According to Wiechowski3
probably
also a formation of allantoin from uric acid takes place in man, but it
is only of such an extent as to be without consideration, while in the dog
for example about 96 per cent of the purine base nitrogen may appear
as allantoin in the urine. According to the investigations of Frank and
Schittenhelm 4
the uric acid in man is in part transformed into urea.
This different behavior of uric acid in the metabolism of man and
animals depends, as numerous investigations 5
have shown, upon the
occurrence of a urocolytic enzyme in the liver and also other organs of
animals, which transforms the uric acid into allantoin with the taking up
oxygen and splitting off of carbon dioxide. This enzyme, which has been
called uricolase and also uricase and whose occurrence in the organs of
different animals varies, is absent in the organs of man. The results
obtained in regard to the enzymotic transformation of uric acid by
experiments with organ extracts must be judged with the greatest care.
Thus according to the statements of Wiechowski, Battelli and Stern
and Schittenhelm,6 in dogs, the liver is the only organ which in a test-
tube shows a positive uricolysis; still in dogs, with excluded livers
(Eck fistula) such an abundant formation of allantoin from uric acid
occurs so that only 10-20 per cent of the uric acid escapes this trans-
formation.7
1
Wohler and Frerichs, Annal. d. Chem. u. Pharm., 65. See also Wiener, Ergeb-
nisse der Physiologie, 1, Abt. 1.
2
Salkowski, Zeitschr. f. physiol. Chem., 35, and Ber. d. d. Chem. Gesellsch., 9;
Mendel and Brown, Amer. Jour, of Physiol., 3; Mendel and White, ibid., 12; Wie-
chowski, Arch. f. exp. Path. u. Pharm., 60, and Bioch. Zeitschr., 19 and 25, with Wiener,
Hofmeister’s Beitrage, 9; Schittenhelm, Zeitschr. f. physiol. Chem., 62, with Seisser,
Zeitschr. f. exp. Path. v. Ther., 7; Abderhalden, London and Schittenhelm, Zeitschr.
f. physiol. Chem., 61.
3
Bioch. Zeitschr., 25.
4
Zeitschr. f. physiol. Chem., 63.
5
Chassevant and Richet, Comp. rend. soc. biolog., 49; Ascoli, Pfliiger’s Arch., 72;
Jacoby, Virchow’s Arch., 157; Wiener, Arch. f. exp. Path. u. Pharm., 42, and Centralbl.
f. Physiol., 18; Schittenhelm, Zeitschr. f. physiol. Chem., 43, 45, and 63; Burian,
ibid., 43; Almagia, Hofmeister’s Beitrage, 7; Pfeiffer, ibid., 7; Wiechowski and Wiener,
ibid., 9; Galeotti, Bioch. Zeitschr., 20; Battelli and Stern, ibid., 19; Scaffidi, ibid.,
18; Miller and Jones, Zeitschr. f. physiol. Chem., 61; Wells, Journ. of biol. Chem., 7,
with Corper, ibid., 6.
6
See Schittenhelm, Zeitschr. f. physiol. Chem., 63, 256.
7
Abderhalden, London and Schittenhelm, 1. c.
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