SPONTANEOUS GENERATION. 593 



hay-germs. The infusion in this case infects itself with- 

 out special inoculation,, and its subsequent resistance to 

 sterilization is often very great. On the 1st of March last 

 I purposely infected the air of our laboratory with the 

 germinal dust of a sapless kind of hay mown in 1875. 

 Ten groups of flasks were charged with turnip infusion 

 prepared in the infected laboratory, and were afterward 

 subjected to the boiling temperature for periods varying 

 from 15 minutes to 240 minutes. Out of the ten groups 

 only one was sterilized that, namely, which had been 

 boiled for four hours. Every flask of the nine groups 

 which had been boiled for 15, 30, 45, 60, 75, 90, 105, 120, 

 and 180 minutes respectively, bred organisms afterward. 

 The same is true of other vegetable infusions. On the 

 28th of February last, for example, I boiled six flasks, 

 containing cucumber infusion prepared in an infected 

 atmosphere, for periods of 15, 30, 45, 60, 120, and 180 

 minutes. Every flask of the group subsequently developed 

 organisms. On the same day, in the case of three flasks, 

 the boiling was prolonged to 240, 300, and 360 minutes; 

 and these three flasks were completely sterilized. Animal 

 infusions, which under ordinary circumstances are rendered 

 infallibly barren by five minutes' boiling, behave like the 

 vegetable infusions in an atmosphere infected with hay- 

 germs. On the 30th of March, for example, five flasks 

 were charged with a clear infusion of beef and boiled for 60 

 minutes, 120 minutes, 180 minutes, 240 minutes, and 300 

 minutes, respectively. Every one of them became subse- 

 quently crowded with organisms, and the same happened 

 to a perfectly pellucid mutton infusion prepared at the 

 same time. The cases are to be numbered by hundreds in 

 which similar powers of resistance were manifested by 

 infusions of the most diverse kinds. 



In the presence of such facts I would ask my colleague 

 whether it is necessary to dwell for a single instant on the 

 one-sided ness of the evidence which led to the conclusion 

 that all living matter has its life destroyed by " the briefest 

 exposure to the influence of boiling water." An infusion 

 proved to be barren by six months' exposure to moteless 

 air maintained at a temperature of 90 degrees Fahr., when 

 inoculated with full-grown active bacteria, fills itself in 

 two days with organisms so sensitive as to be killed by a 

 few minutes' exposure to a temperature much below that 



