555 
Variation of Yeast-cells. 
We are now going to mention some experiments, by means 
of which varieties were produced in another manner than that 
described above, and with other properties. 
If yeast-cells are living on the surface of nutritive gelatine, 
they are exposed to quite different conditions from those 
which obtain when, for instance, they are living in wort, and 
the new generations produced under these special circumstances 
therefore also acquire a special character. Two varieties, a and 
of the Carlsberg bottom-yeast, No. i, were partly cultivated 
in wort, partly on the surface of wort-gelatine, the cultures 
being renewed fairly frequently during some months. On the 
gelatine new varieties developed having a greater fermentative 
power than their primitive forms. In wort to which cane- 
sugar had been added, the latter only produced about 13 per 
cent, (by volume) of alcohol, while the new varieties produced 
13-6 per cent. In this experiment only vegetative cells were 
made use of. 
A more marked difference, in the same direction, appeared 
in some experiments which I made with the top-fermentation 
yeast Saccharomyces cerevisiae , I. They were arranged in the 
same manner as the foregoing experiments, but the cultures 
were here made from spores, and instead of wort-gelatine, 
yeast-water gelatine was used. The growth which was culti- 
vated on gelatine in this case gave 3 per cent, of alcohol more 
than the corresponding growth which had been cultivated 
in wort. 
Before leaving these experiments, I must emphasize the fact 
that the gelatine varieties produced were all descended from 
varieties which, as long as they were cultivated in wort, were 
very constant, and were distinguished by producing only a 
comparatively small percentage of alcohol. 
Another way in which we may operate on yeast-cells in the 
direction mentioned, is by the action of antiseptics. In 1887 
Biernacki arrived at the conclusion that all antiseptics, when 
employed in small quantity and under certain conditions, 
possess the property of accelerating and strengthening alco- 
holic fermentation. Maercker’s and Hayduck’s investigations 
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