ORIGIN OF LOWEST ORGANISMS. 53 



clear. This latter flask was opened on the twelfth 

 day, whilst its contents were still clear, and on micro- 

 scopical examination of the fluid no living Bacteria 

 were to be found. This particular experiment was 

 repeated three times with similarly negative results, 

 although on two occasions the fluid was only boiled 

 for one minute instead of ten. 



It seemed, moreover, that by having recourse to ex- 

 periments of the same kind, the exact degree of heat, 

 which is fatal to Bacteria and Torulcz might be ascer- 

 tained. I accordingly endeavoured to determine 

 this point. Portions of the same saline solution, 

 after having been boiled * and allowed to cool, 

 were similarly inoculated with a dropj of very 

 turbid fluid, containing hundreds of living Bacteria, 

 Vibriones, and Torula. A drying apparatus was fixed 

 to an air-pump, and the flask containing the inoculated 

 fluid was securely connected with the former by 

 means of a piece of tight india-rubber tubing,J after 

 its neck had been drawn out and narrowed, at about 

 two inches from the extremity. The flask containing 



* It was necessary to boil the solution first, in order to destroy 

 any living things or dead ferments which it might contain. It 

 must contain one or the other, because an unboiled solution of 

 this kind, in a corked bottle about half full, will always become 

 turbid ; whilst, after it has been boiled, it may be kept indefi- 

 nitely under similar conditions without becoming turbid. 



f The proportion was one drop of the fluid, opaque with or- 

 ganisms, to an ounce of the clear solution. 



J Into which apiece of glass tube had been slipped to prevent 

 collapse. 



