495 
Enzyme of Yeast. 
disturbance by yeast-cells, if any should have escaped 
detection, I added an excess of chloroform, shaking it well. 
The flask had a side-tube, closed by a clip, by which I was 
able to equalize the pressure within and without in case any 
difference should appear. The outlets were closed with 
stoppers of sterilized cotton-wool, and the whole apparatus 
was sterilized carefully before putting the extract and sugar- 
solution into it. 
After letting it stand about half an hour to recover from 
the shaking with the chloroform, the pressure was adjusted, 
and the flask left at the temperature of the laboratory. In 
less than another half-hour there was an internal pressure 
in the flask which displaced the mercury in the manometer 
•5 inch. As time went on, this displacement increased until 
all the mercury was driven into the distal limb ; and then, on 
gently shaking the flask, the generated gas escaped through 
the mercury-column. 
At the end of twenty-four hours the chloroform had pro- 
duced a copious precipitate of proteid matter in the flask. 
I rapidly extracted some of this precipitate, fearing it might 
be a growth of yeast. Microscopic examination showed that 
it was free from yeast-cells, and consisted of a fine amorphous 
powder. It 'is well known, of course, that yeast-cells will not 
grow in a saccharine liquid saturated with chloroform. 
On the third day I divided the contents of the flask into 
two, and filtered half of it through filter-paper to get rid of 
the proteid precipitate. Fermentation was active in the 
liquid before opening the flask, the pressure supporting 
i *5 inch of mercury in the manometer. I then put the filtered 
and the unfiltered halves side by side in similar flasks, and 
left them again at the temperature of the laboratory. Next 
morning the flask containing the filtered liquid showed very 
little alteration of level in the manometer, and on shaking 
only a slight amount of gas escaped from the liquid, only 
enough indeed to displace the level of the mercury about 
•25 inch. 
On shaking the flask containing the un filtered liquid, on 
