VITALITY OF PUTEEFACTIVE OBGANISMS. 173 



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 re- 

 moval 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 contained 

 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 its 

 pipette-shank filled with air. In a fourth chamber 

 only one inch of the pipette-shank was filled with air ; 

 here one out of a total of three tubes remained pellucid. 

 Thus, where the closure above was perfect, we had in 

 this instance perfectly pellucid infusions ; where it was 

 grossly defective, the infusions gave way in all the tubes ; 



