APPENDIX. 333 



abundantly demonstrated that the process of alcoholic fer- 

 mentation depends on the continuance of life without air — 

 other organisms than Torula being also alleged to be com- 

 petent to live -without oxygen. Experiment alone could 

 determine the effect of exhaustion upon the particular 

 organisms here under review. 



Air-pump vacua were first employed, and with a con- 

 siderable measure of success. Life was demonstrably 

 enfeebled in such vacua. 



Sprengel pumps were afterwards used to remove more 

 effectually both the air dissolved in the infusions and that 

 diffused in the spaces above them. The periods of ex- 

 haustion varied from one to eight hours, and the results of 

 the experiments may be thus summed up : — Could the air 

 be completely removed from the infusions, there is every 

 reason to believe that sterilization ivitJwut hoiling would in 

 most, if not in all, cases be the result. But, passing from 

 probabilities to certainties, it is a proved fact that in 

 numerous cases unboiled infusions deprived of air by five 

 or six hours' action of the Sprengel pump are reduced to 

 permanent barrenness. In a great number of cases, more- 

 over, where the unboiled infusion would have become 

 cloudy, exposure to the boiling temperature for a single 

 minute sufficed completely to destroy the life already on 

 the point of being extinguished through defect of air. 

 With a single exception, I am not sure that any infasion 

 escaped sterilization by five minutes' boiling after it had 

 been deprived of air by the Sprengel pump. These five 

 minutes accomplished what five hours sometimes failed to 

 accomplish in the presence of air. 



The exception here referred to is old-hay infusion, 

 which, though sterilized in less than half the time needed 

 to kill its germs where air is present, maintained a power 

 of developing a feeble but distinct life after having been 

 boiled for a large multiple of the time found sufficient to 

 render infusions of mutton, beef, pork, cucumber, turnip, 

 beetroot, shaddock, and artichoke permanently barren. 



These experiments gave me the clue to many others 



