PERSISTENCE OF PUTREFACTIVE AND INFECTIVE ORGANISMS. 
173 
gas-stove, at about 90° Fahr. — a temperature which had been proved eminently favour- 
able to the development of Bacteria. 
Tubes containing the same infusions were at the same time exposed to the common 
air of the Jodrell laboratory. These became rapidly turbid and covered with scum. 
Anxiously inspected during the early days of their trial, the protected tubes showed no 
signs of giving way. Nor did they yield afterwards. On the 19th of January the four 
chambers were removed in a van from Kew, and shown in the evening of that day to 
the members of the Royal Institution, including many Fellows of the Royal Society. 
The infusions were one and all brilliant, no trace either of turbidity or scum being found 
associated with any of them. During all my previous efforts (and they had been very 
numerous) I had never succeeded in saving a single tube of melon-infusion ; here, how- 
ever, every tube of both chambers was intact. The epidemic was thus localized, the 
obvious cause of it being the contaminated air of our laboratory. 
A couple of days subsequent to the removal of the chambers from Kew, a single tube 
of the cucumber-infusion became turbid, its two neighbours in the same chamber 
remaining intact. As long as they were kept quiet not one of the other tubes, either of 
melon or cucumber, gave way. They all remained as pellucid as at first. Their removal 
from Albemarle Street to the city last year ruined many of our sterilized chambers. 
I was not therefore prepared to see so little damage done by the transport from Kew. 
It may be remarked, in passing, that this infection of an infusion by mere mecha- 
nical shaking is an obvious proof that the contagium is not a gas or vapour, but 
that it consists of particles capable of being detached from the interior surface of the 
chamber, and endowed with the power of passing into active life. 
Two other chambers were exposed at the same time in the Jodrell laboratory, the 
one containing beef- and the other sole-infusion. They are by no means so sensitive as 
the cucumber and melon, still one of the three beef-tubes broke down, becoming thickly 
turbid throughout. Right and left of this tube its two companions remained perfectly 
transparent. As an illustration of the externality of the contagium, the result was 
more conclusive than it would have been had all three tubes remained intact; for 
had the power of developing the organisms which produced the turbidity been inherent 
in the infusions, its action would not have been confined to a single tube. 
It will be understood that when the chamber is lifted from the oil-bath in which its 
infusions are boiled, the air within the chamber contracts, and an indraught is the 
consequence. If the entering air be properly sifted, by passing it through cotton-wool 
plugs, no harm is done ; but if it enter an aperture unsifted, it carries its motes along 
with it. In the beef-chamber just referred to an aperture of this kind, about the size 
of a pin-hole, was detected. This obviously was the door through which the contagium 
entered. Through a similar but graver defect in its chamber the sole-infusion also 
broke down; but in a subsequent experiment with sole-infusion in the Jodrell labora- 
tory, two thirds of the whole number of tubes charged with it remained free from all 
trace of life. 
MDCCCLXXVII. 
2c 
