DISCUSSION WITH BASTIAN 117 



At this time, fortunately, Pasteur had already con- 

 ceived the idea of the spore, the egg of the Infusorian, 

 which demands other conditions for its existence than 

 those with which the Infusorian itself is content. The 

 conditions of this revivification are in general limited, 

 and each species has its own. Because of this fact, and 

 because sometimes these conditions are very delicate, 

 it is possible occasionally for two scientific men who 

 work on the same species to find that they are in disagree- 

 ment, because of an insignificant difference in their 

 method of work. Because of the fact that the condi- 

 tions vary with the species, it is clear that these savants 

 will be still more likely to contradict each other if they 

 work, as is almost always the case, on different species, 

 and behold herein a hitherto scarcely dreamed-of ex- 

 planation of a multitude of contradictions in the experi- 

 mental study of spontaneous generations. 



This element of mystery, now revealed, was calculated 

 to arouse zeal in the laboratory of Pasteur. It was soon 

 recognized there that two conditions govern the re- 

 juvenescence of the germ, the reaction of the liquid 

 and the presence of air. This was especially the work of 

 Chamberland. In a liquid which is too acid, germs 

 heated to 100 C. remain alive, but inert. Diminishing 

 or neutralizing the acidity opens the field for them. 

 This is what Bastian did, and his experiment contained 

 nothing contradictory to the germ theory. It is true 

 that, by way of retaliation, he ought to have recognized 

 the existence of living germs in the flasks which Pasteur 

 regarded as sterile, and from which he deduced evidence 

 against spontaneous generation. But the evidence re- 

 mained good, although the witness was untrustworthy: 

 heating to 115 or 120 C. the liquids which Pasteur had 

 been content to heat to the boiling point, sufficed to 

 destroy everything that was living therein, and to give 



