Saccharomyces anomalus [Hansen). 227 
in an atmosphere of hydrogen instead of in vacuo , the presence 
of pyrogallic acid and potash causing growth to cease, while 
in its absence growth takes place as usual. 
These experiments seem to prove that the growth of the 
organism depends on the presence of free oxygen, since when 
the last traces of the free gas are absorbed by the alkaline 
solution of pyrogallic acid, growth is inhibited. 
Other experiments bearing on the same point were made, 
using fermentation-tubes 1 . These were filled with sterilized 
beer-wort and infected with the Yeast. It was found that 
when active fermentation was in progress, that gas frequently 
accumulated in the vertical closed tube. At first this was 
taken as indicating the anaerobic power of the Yeast, but this 
fact being at variance with the results of the experiments 
mentioned above, led to a repetition of the experiment. The 
same results were obtained when active fermentation set in, 
but it was noticed that the beer-wort in the vertical closed 
tube, instead of becoming cloudy, as one would expect if the 
Yeast were anaerobic and therefore were developing in that 
portion of the liquid, remained quite clear. The fermentation- 
tube was allowed to stand until active fermentation had 
ceased, and then it was noticed that the gas in the vertical 
closed tube was gradually absorbed again, until not more 
than one-twentieth part of the original volume remained. This 
was not absorbed, although the tube was allowed to stand for 
four weeks. The experiment was again repeated, and exactly 
the same results obtained. The explanation seems to be that 
at the beginning of active fermentation the evolution of carbon 
dioxide is so rapid that a portion of it strikes against the 
curved surface and rises by accident into the closed tube, and 
this is not absorbed until active fermentation has ceased, on 
account of the continuous evolution of the gas going on during 
that period. When this evolution stops, however, the liquid, 
if not fully saturated with the gas, gradually absorbs that 
portion contained in the tube. 
Liquefaction of gelatine. The Yeast is capable of liquefying 
1 See Theobald Smith ( 23 ). 
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