BACTERIA AND THEIR GERMS. 89 
It was pointed out by Gruithuisen early in the 
present century, that many infusions, otherwise very 
productive, ceased to be so when they were poured 
into a glass vessel whilst boiling, and when this was 
filled so that the tightly-fitting stopper touched the 
fluid. Having myself proved the truth of this asser- 
tion for hay-infusion, it seemed likely that, by having 
recourse to a method of this kind, I should be able to 
lower the virtues of boiled hay- and turnip-infusions, 
to the level of those possessed by the boiled saline 
solution with which I had previously experimented— 
that is, to reduce them to.a state in which, whilst they 
appear (under these conditions) quite unable of them- 
selves to engender Bacteria, Vibriones, they continue 
well capable of favouring the rapid multiplication of 
such organisms. 
This was found to be the case; and I have 
accordingly performed upwards of one hundred ex- 
periments with inoculated portions of these two 
infusions raised to different temperatures. The 
mode in which the experiments were conducted was 
as follows :— 
Infusions of hay and turnip of slightly different 
strengths were employed. These infusions, having 
been first loosely strained through muslin, were 
boiled for about ten or fifteen minutes, and then 
whilst boiling strained through ordinary Swedish 
filtering-paper into a glass beaker which had pre- 
