) 
et 0.1] B. lactis aérogenes on Glucose and Mannitol. 283 
interesting, and is quite analogous to the bacterial oxidation of mannitol to 
fructose (Vincent and Delachanal),* sorbitol to sorbose, and glycerol to 
dihydroxyacetone (Bertrand).t 
The Arrangement of the Experiments. 
Two similar flasks were filled with the same medium. 
Glucose, 50 grm. 
In Experiment I ...... | Wie peptone, 10 grm. > Water to 1 litre. 
Chalk, 15 orm. 
Butyleneglycol, 8 grm. 
In Experiment II ... 
n Experiment I Witte peptone, 10 grm. 
} Water to 1 litre. 
One, after sterilisation, was freed completely from oxygen in the manner 
described,t inoculated, fitted with a mercury trap, and incubated at 37° for 
21 days. 
The other, also after sterilisation, was inoculated and incubated at 37° for 
22 days, but a stream of oxygen from a cylinder fitted with a reducing valve, 
after passing through two wash bottles containing water and kept at 37°, was 
bubbled through it the whole time at the rate of about 50 c.c. per minute. 
The volume of the contents of the flask scarcely changed during the passage 
of the gas. The oxygen after leaving the flask passed again through wash 
bottles kept. cold by circulation of the main supply (12° C.) and up an 
inverted condenser. Any acetylmethylearbinol carried over by the oxygen 
was thus trapped. In Experiment I the proportion of carbon dioxide in the 
gas leaving the apparatus never exceeded 2 per cent. 
The Examination of the Media after Fermentation. 
Experiment I—The glucose in the residues after distillation was 
determined by Pavy’s method after removal of protein by mercuric nitrate 
and excess of mercury by caustic soda. The residual sugar in the anaérobic 
culture was less than 3 erm.; that in the aérobic culture was less than 
0-6 grm. 
The comparison of the amounts of acetylmethylcearbinol produced in the 
two cases was conducted as follows. The contents of the two flasks were 
filtered from unattacked CaCO3 and insoluble calcium salts and the filtrates 
distilled until in each case 800 cc. of distillate were collected. Very small 
traces of acetylmethylcarbinol can be detected by Fehling’s solution, and 
previous experience with this substance demonstrated that such a distillate 
* “Compt. Rend.,’ 1897, vol. 125, pp. 716—717. 
t ‘Ann. Chim. Phys.,’ 1904, 18, vol. 3, pp. 181—288. 
{ ‘Jenner Inst. Trans.,’ 1899, vol. 2, p. 129. 
