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-sidedness 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 
