OR1GIX OF LOWEST ORGANISMS. 105 



to a much larger quantity of calcined air, there may 

 be strong reason for coming to an opinion similar to 

 that of Gay-Lussac. When, however, it is also 

 ascertained that provisions which have been subjected 

 to the long-continued influence of heat, do not undergo 

 change in closed vessels, if all air has been expelled 

 from the very small space above the level of the pro- 

 visions ; though many organic infusions will putrefy 

 if they occupy only one half, or less, of a hermetically 

 closed vessel from which all air has been similarly ex- 

 pelled by ebullition of its fluid contents, it is impos- 

 sible that the same explanation can hold good. And 

 at the same time another interpretation is suggested 

 for the first set of facts. 



The last-mentioned experiments prove * that fer- 

 mentation can take place in vacuo, when the 

 conditions are more favourable than those which 

 present themselves within the almost full tins con- 

 taining provisions. The change in these latter cases 

 cannot (in the great majority of instances) proceed 

 fart, because there is no adequate space into which 



* This proof is more severe in certain other experiments (not 

 yet published) in which I had the benefit of Professor Frankland's 

 assistance. The vacuum in these cases was perhaps more per- 

 fect, having been procured by means of a Sprengel's pump and 

 a simultaneous ebullition of the fluid, during which the flasks 

 were hermetically sealed. The closed flasks were subsequently 

 exposed to a temperature of 293 F. for a short time. 



f An examination of tins of " perfectly good " meats has con- 

 vinced me that a very small number of Bacteria and Leptothrix 

 filaments are occasionally to be met with. 



