158 
ANNALES DE L’INSTITUT PASTEUR 
Hence glucose is expected to yield d. lactic acid and man¬ 
nose d. I. lactic acid. 
On the basis of these considérations leucocytes were allowed 
to act on glucose, mannose, fructose and galactose? It was 
found that only one form of lactic acid, namely d. lactid acid 
was produced in every experiment. On the basis of this it 
seemed suggestive lliât glyceric aldéhyde is converted into 
lacticacid through the intermediate formation of melhylglyoxal. 
To give more weight to this hypothesis it was necessary to 
demonstrate experimenlally that methylglyoxal can be trans- 
formed into d. lactic acid Ihrough the aclion of leucocytes. 
The experiment was carried out and the resuit was as expected. 
Simullaneoiisly and independentiy of us Dakin and Dudly 
hâve shown that metliylglyoxal can be Iransformed inîo lactic 
acid by other animal tissues. The same observation was later 
made by Neuberg. However it must be admitted that the 
intermediate formation of glyceric aldéhyde as a precursor to 
methylglyoxal is not detinitely proven, neilhe* theoretically 
nor experimenlally. Its formation is a possibility. Methyl¬ 
glyoxal may also be formed through the following hypothetic 
intermediate phase : 
CHO 
CHO 
I 
CO H 
H - 
G OII 
— II 
COH 
COH 
1 
1 
II 
II 
OH — 
G — II 
OU 
CII 
ch 2 
1 
1 
H — 
G — OH 
Il — GO H 
CHO 
H - 
G — OH 
— H 
COH 
j 
COU 
1 
1 
II 
II 
CH,OH 
OH 
CH 2 
ch 2 
However the true intermediate sleps which lead fo the for¬ 
mation of melhylglyoxal from hexose still remain in the realm 
of conjecture. An attempt was made to bring the problem 
nearer solution in the following manner. The glycolytic enzyme 
was allowed to act on sugar in which the hydrogen of one or of 
more than one hydroxyl group was substituled by other radi- 
cles. The substances employed in the course of these expe- 
riments were the following : tetramethylglucose, a and 3 
methylglucosides, lactose, sucrose, maltose and glucose-phos- 
phoric acid. They are ail dérivatives of glucose. In the first 
