INTR OD UCTION. 25 



decomposing fluids was always to be explained either 

 by the pre-existence of similar living forms in the in- 

 fusion or upon the walls of the vessel containing it, or 

 by the infusion having been exposed to air which was 

 contaminated with organisms. 



These facts have since been practically confirmed on 

 an enormous scale in the preservation of food by the 

 process of sterilization. Indeed, there is scarcely any 

 biological problem which has been so satisfactorily 

 solved or in which such uniform results have been ob- 

 tained ; but all through the experiments of the earlier 

 investigators irregularities were constantly appearing. 

 Although in the large majority of cases it was found 

 possible to keep boiled organic liquids sterile in flasks 

 to which the oxygen of the air had free access, the 

 question of spontaneous generation still remained un- 

 settled, inasmuch as occasionally, even under the most 

 careful precautions, decomposition did occur in such 

 boiled liquids. 



This fact was explained by Pasteur in I860 by ex- 

 periments showing that the temperature of boiling 

 water was not sufficient to destroy all living organ- 

 isms, and that, especially in alkaline liquids, a higher 

 temperature was required to insure sterilization. He 

 showed that at a temperature of 110 to 112 C. (230 

 to 233 F.), however, which he obtained by boiling 

 under a pressure of one and one-half atmospheres, all 

 living organisms were invariably killed. 



Pasteur at a later date (1865) demonstrated that the 

 organisms which resist the boiling temperature are, in 

 fact, reproductive bodies, which he described under the 

 name of " corpuscles ovoides " or " corpuscles bril- 

 lants " now known as spores. Perty, in 1852, and 



