333 
be different; for numerous experiments show that super- 
heated liquids, and particularly Pasteur’s solution, when 
freely exposed to the air in a watch glass or 
an open tube, become eventually covered with 
tufts of penicillium. 
In the further progress of the inquiry it was 
found entirely unnecessary to employ so high a 
temperature as 170° to 200° C. in order to pre- 
vent the evolution of organic forms, provided 
that the liquids were protected from contamina- 
tion by external media. The experiments which 
led to this result were as follows :— 
V.—August 10.—A number of tubes were 
filled with serum of rabbits’ or sheep’s blood. 
They were then sealed and boiled for an hour 
or two ina water bath, in consequence of which 
the liquid contained in several of the tubes 
became gelatinous, still, however, remaining 
perfectly transparent. From time to time during 
the next few months a tube was broken for 
microscopical examination of its contents, the 
result being always negative. In March, 1871, 
the remaining tubes were finally examined. No 
organic forms could be traced either in those 
which were gelatinous or in those which re- 
mained liquid. 
VI.—October 5.—Pasteur’s solution was pre- 
pared according to formula (the distilled water 
employed for the purpose being obtained from 
Messrs. Hopkin and Williams), and placed in 
a clean capsule. A number of tubes of various 
sizes were then filled, in the manner already 
described, with the solution (which had not 
been heated), and sealed. The solution was 
then boiled in the capsule for a few minutes, 
and another batch of tubes were filled in the 
same manner by breaking their points under- 
neath the surface of the liquid while it was 
still in a state of ebullition. Each tube was 
sealed the moment it was withdrawn from the 
boiling liquid. The two sets of tubes were 
placed side by side in the laboratory under 
. precisely similar conditions. Some of them were examined 
microscopically on the 17th. In those of the first batch 
microzymes in immense numbers, and torula cells, were 
found along with several filaments of sporotrichum. No 
Via. 1. Tube used in this and the following experiments; the tube is shown in the closed state, and of the actual size. 
