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LACTIC ACID FORMATION FROM SUGAR. 333
speak positively for the statement that in glycolysis a formation of lactic
acid from the sugar occurs.
That a formation of lactic acid from glucose, and indeed by means of
the leucocytes, takes place in glycolysis was shown by Levene and Meyer
before Embden and collaborators. On continuing these investigations
Levene and Meyer found that fructose as well as mannose and galactose
under the same conditions with leucocytes, yield d-lactic acid while with
the investigated pentoses, arabinose and xylose, this is not the case. Accord-
ing to Embden and co-workers, this formation of lactic acid takes place
probably with glyceric aldehyde, and perhaps also with small amounts
of dioxyacetone, as intermediary steps, and a formation of lactic acid from
glyceric aldehyde (and dioxyacetone) can in fact, as A. Loeb and Gries-
bach l
have shown, be brought about by enzymotic means by the form-
elements of the blood. It seems as if several enzymes were active in the
formation of lactic acid from glucose. According to Loeb those varieties
of blood which show no glycolysis with the formation of lactic acid, or
none worth mentioning, can form lactic acid from glyceric aldehyde
and according to Griesbach in this last -mentioned process an enzyme
is active which is soluble in water and resistant toward the haemolysis
of the blood with water, while the action of the blood upon glucose is
destroyed in the destruction of the form-elements by haemolysis. In
regard to the formation of lactic acid from methyl glyoxal see page 584.
According to Lepine and Boulud a double process takes place in the
glycolysis. On one side the sugar is destroyed and on the other side
a re-formation of sugar from the "sucre virtuel" takes place. Hereby the
actual glycolysis may be greater than the visible, and the mentioned
investigators have therefore suggested a method for determining the
extent of the actual glycolysis.2
The quantity of urea, which, according to Schondorff, is equally
divided between the blood-corpuscles and the plasma, is greater on tak-
ing food than in starvation (Grehant and Quinquatid, Schondorff)
and varies between 0.2 and 1.5 p. m. In dogs Schondorff found in
starvation a minimum of 0.348 p. m. and a maximum of 1.529 p. m. at
the point of highest urea formation. Gottlieb obtained much lower
results by another direct method, namely, in starvation 0.1-0.2, and
after meat feeding 0.28-0.56 p. m., Folin and Denis found 0.3-0.77
p. m. in the Mood of the cat. In man v. Jaksch 3
found 0.5-0.6 p. m.
1
Levene and Meyer, Journ. of biol. Chem., 11 and 14; A. Loeb, Bioch. Zeitschr.
49 and 50; Griesbach, ibid., 50.
2
Lepine and Boulud, Journ. de Physiol., et de Path. gene>ale, 13.
8
Grehant et Quinquaud, Journ. de l’anatomie et de la physiol., 20, and Compt.
Rend., 98; Schondorff, Pfliiger’s Arch., 54 and 63; Gottlieb, Arch. f. exp. Path. u.
Pharm., 42; Folin and Denis, Journ. of biol. Chem., 11 and 12; v. Jaksch, Leyden-
Fetschr., I, 1901.
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