PERSISTENCE OF PUTREFACTIVE AND INFECTIVE ORGANISMS. 
171 
shank below the stopcock was supported by atmospheric pressure. A pinchcock nipped 
the india-rubber tube at its centre. The portion of tubing above the pinchcock being 
filled with the infusion, the end of the separation-funnel was introduced into the tube, 
all air being thus excluded. On turning on the stopcock and releasing the pinchcock, 
the liquid passed slowly down the shank of the pipette, filling it wholly. The point of 
the shank was then placed in succession over the test-tubes, the infusion entering them 
without a single associated bubble. The arrangement was not perfect, but it was an 
improvement upon previous ones. As before, the charged chambers were placed in a 
room the air of which was maintained at a temperature of about 90° Fahr. 
The result was as follows: — Of the two turnip chambers prepared, as just described, 
on the 4th, one had completely given way on the 6th. In the other chamber two out 
of the three tubes had given way, but the third remained permanently brilliant. Pre- 
vious to this series of experiments I had never succeeded in saving even a single tube of 
cucumber-infusion ; here, however, two out of the three chambers charged with it 
remained perfectly clear for many days. Subsequently one of these chambers yielded 
in part, through an accident, but the other chamber is as brilliant at this moment as it 
was on the day of its preparation many months ago. 
Now, as regards inherent power to generate life, the infusion of this chamber was in 
precisely the same condition as its two neighbours. They, one and all, contained the 
same infusion ; and there is no way of accounting for the observed difference of deport- 
ment save by reference to contamination from without. Here we seem to be on the 
traces of the enemy which has given us so much trouble. 
On the 5th of December two additional cases were charged with infusion of melon 
prepared in the usual way; and on the 12th of December I subjected both these 
chambers, and those prepared upon the 4th, to a very close scrutiny. The result was 
instructive. After the introduction of the infusions, and prior to the removal of the 
separation-funnel, the india-rubber tubing connecting the latter with the shank of the 
pipette was perfectly closed by the pinchcock. Provided the clasping of the india- 
rubber tube round the shank of the pipette were perfectly air-tight, the liquid con- 
tained in the shank ought to remain there, supported by atmospheric pressure. If, 
however, the india-rubber tube failed to clasp with sufficient tightness the pipette-shank, 
air would insinuate itself between the two, and the depression of the liquid would be 
the consequence. The result observed upon the 12th was this: — In two only of the 
seven chambers prepared on the 4th and 5th was the liquid column found perfectly 
supported ; and only in these two chambers were the test-tubes, which contained 
cucumber-infusion, without exception pellucid. 
In the five remaining chambers the liquid columns, which had completely filled the 
pipette-shanks on the 4th and 5th, were found more or less depressed. The tubes in 
one of the chambers, containing melon-infusion, had become rapidly turbid and covered 
with scum. The pipette-shank in this case was found entirely emptied of its liquid and 
filled with air. Another chamber had nine inches, while a third had seven inches of 
