INTRODUCTION. 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 1860 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 
