PERSISTENCE OF PUTREFACTIVE AND INFECTIVE ORGANISMS. 
151 
the objection. Other temperatures, higher than any previously employed, were at the 
same time said to ensure spontaneous generation. I exposed my infusions to these 
newly discovered efficient temperatures, but found that they remained as barren as 
before. 
With regard, moreover, to the question of concentration, it was shown that, owing to 
their gradual vaporization, the infusions used by me were probably unequalled in strength 
by those employed by any previous investigator. Some of these infusions remain with me 
to the present hour. Concentrated by twelve months’ slow evaporation, and reduced to 
one fifth of their primitive volume, they still exhibit the purity of distilled water. 
These results have been published in the Philosophical Transactions, and Dr. Bastian 
has made no attempt to invalidate them. They prove beyond a doubt that in the atmo- 
spheric conditions existing in the laboratory of the Royal Institution during the autumn, 
winter, and spring of 1875-76, five minutes’ boiling sufficed to sterilize organic liquids 
of the most diverse kinds. Among these may be mentioned urine in its natural condi- 
tion, infusions of mutton, beef, pork, hay, turnip, haddock, sole, salmon, cod-fish, turbot, 
mullet, herring, eel, oyster, whiting, liver, kidney, hare, rabbit, barn-door fowl, grouse, 
and pheasant. Once properly sterilized, and protected afterwards from the floating 
matter of the air, not one of these putrescible infusions ever manifested the power of 
generating by its own inherent energy putrefactive organisms of any kind. 
§ 2. Experiments of Pasteur, Roberts, and Cohn. 
During the investigation just referred to I confined myself for the most part to 
animal and vegetable juices in their natural condition — that is to say, extracted by dis- 
tilled water, and not rendered artificially acid, neutral, or alkaline. I had occasion, 
how’ever, to repeat among others some of the very remarkable experiments on super- 
neutralized hay-infusions described by Dr. Wm. Roberts in his excellent paper in the 
Philosophical Transactions for 1874. These experiments I could not corroborate; for 
while in his hands such infusions sometimes required three hours’ boiling to sterilize 
them, in mine they behaved like other infusions, and were sterilized in five minutes. 
In the abstract of the investigation communicated to the Royal Society on the 13th 
of January, 1876, I mentioned this discrepancy, and pointed out its possible cause *. 
But the largeness of the question, which had been long previously raised by M. Pasteur, 
and the limitation of my time led me to postpone it. This postponement is mentioned 
at the conclusion of my paper in the Philosophical Transactions, where the discrepancy 
referred to is not at all discussed. 
In his celebrated paper, “ Sur les corpuscules organises qui existent dans l’Atmo- 
sphere,” published fifteen years agof, M. Pasteur first announced that while acid 
infusions had their germinal life destroyed by a temperature of 100° C., a temperature 
over 100° was needed to produce the same effect in alkaline infusions. In his 4 Etudes 
sur la Biere,’ published in the early part of 1876, he repeats and illustrates this statement. 
* Roy. Soc. Proc. vol. xxrv. p. 178. f Annates de Chimie, 1862, vol. Ixiv. 
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