In experiments with fresh juice from dry yeast of March 1916 and : 
and anisic aldehyde proved to be particularly effective. eet : 
Likewise, with fresh juice from yeast of September 1916 and dectroser { 
cuminic ae and the phthalic dialdehydes manifested themselves as” 
reacts as the tautomeric 0) uy drecaiieione fe ‘ 
Experiments with juice, 24 hours old, from yeast of Séptertihet 1916, ne a 
ketones were negative, as was the test with methyl m-hexyl ketone. = ea 
From an experiment with fresh juice from dry yeast of September 1916 and dextr } 
with addition of propionic aldehyde in various concentrations, and at low temperatur 
(11 to 12°) it was found that with the simple aldehydes, the most favourable concentra- 
tion for bringing about the activity is, in general, near the concentration aati : 
These experiments were followed by comparative tests with fresh juice fone 
yeast of September 1915 and dextrose and with equimolecular quantities of ‘su 
aldehydes as were considered to be typical representatives of each series; the rise 
in the fermentation-speed observed on addition of the aldehydic activators. ‘to. ee 
various mixtures was found to range between 800 and 1200 p.c. i 
On activating the dextrose fermentation-process by means of different typical aldehydes 
added in molecular concentration all the aldehydes investigated (with exception of form- q 
aldehyde, which in this concentration stops the fermentation) manifested their activating 
effect, e.y., after 30 minutes or one hour. With benzaldehyde and asovaleric aldehyde, 
however, the activation was retarded at the beginning of the second hour, nevertheless, o | 
furfural and cenanthol showed their beneficial influence under these abnormal conditio 
In a mixture of 13 g., a content of 0.1552 g. of the high-molecular citral is a ac 
When activating the fermentation of dextrose with typical alten in) 
centration, the strong action of formaldehyde was striking. 
In the fermentation of mannose, the simple aldehydes and dialdehydes, in accord 
_with the results observed on fermenting dextrose proved likewise to be fully effecti - 
Mannose is particularly suited for studying the stimulating action, as under the co - 
ditions ruling its fermentation proceeds somewhat slower than with dextrose. "4 
Comparative tests, at 18.5°, with juice from. dry yeast and bs By be: solution 
levulose showed no noticeable effect on addition of aldehydes in 75 concentration. Has 
m 
the mixtures with ; furfural, 55 acetalienNec: and 75 cenanthol, fermentation 
10_ 
aldehyde, in 5, concentration, retarded the vivid fornentanas of ms ee 
solution. The author therefore lowered the temperature as well as the stre 
activators and diluted at the same time the yeast juice with 100 p.c. water. — 
tion was not very marked, yet sufficient so as to remove any Mee is on the 
of activating the fermentation of levulose. — ole 
With cane sugar, the proof of the activating effect, in accord wit 
fermentition, is brought about best at low Saal tania and by usin; a yeas cd 
diluted to half its strength. 6 GGA a aS | 
ze dire 
s 
