ATMOSPHERE IN RELATION TO PUTREFACTION AND INFECTION. 
33 
introduced into three tubes protected by a chamber of 451 cubic inches capacity. It 
was boiled for five minutes in a brine-bath. Three exposed tubes, containing the same 
infusion, were placed beside the protected ones. On the 5th the exposed tubes showed 
signs of haziness, on the 6 th they were turbid, of a green colour, and filled with Bacteria. 
They have maintained their muddiness, colour, and swarming life up to the present time. 
While the exposed beef-infusion putrified in this way, all the protected infusions 
remained perfectly sweet and clear. 
§ 6. Haddock-Infusion. 
The haddock was cut up and digested on the 24th of September ; it was afterwards 
introduced into six tubes, protected by a chamber. On boiling, its albumen, like that 
of the mutton first referred to, coagulated and sank to the bottom, leaving a perfectly 
clear liquid behind. Six .exposed tubes filled with the same infusion were placed 
beside the six protected ones. 
On the 27th the exposed tubes were all turbid and swarming with Bacteria. On the 
29th one of the tubes showed a fine green colour ; three other tubes showed the same 
colour afterwards. The vivacity of the organisms was extraordinary, and their shapes 
various. They darted rapidly to and fro across the field, clashing, recoiling, and 
pirouetting — rendering it, indeed, difficult to believe in the vegetable nature which the 
best microscopists assign to them. 
For nearly three weeks the protected tubes remained perfectly clear. To gain room, 
the case was subsequently shifted, and soon afterwards one of the six tubes became 
turbid. Something, doubtless, had been shaken into it from the top of the chamber. 
For more than a month this single infected flask remained in company with the five 
healthy ones. The air containing the products of putrefaction had free access to the 
whole of them, but there was no spread of the infection. As long as the organisms 
themselves were kept out of the flasks, the “ sewer-gas ” developed by the putrefaction had 
no infective power. On the 14th of November I infected two perfectly pellucid tubes 
with haddock-infusion which, after boiling, had been exposed for two days to the air. 
On the 15th the two tubes had obviously yielded to the infection. On the 16th disease, 
if I may use the term, had completely taken possession of them. Into one of them 
only one or two drops of the turbid infusion had fallen, while ten times this amount 
was introduced into the other. Nevertheless on the 16th both appeared equally turbid. 
The infection acted exactly like the virus of smallpox, a small quantity of which will 
in the long run produce the same effect as a large one. 
§ 7. Turnip-Infusion. 
Turnip-juice had a special interest for me in consequence of the important part it 
plays in the experiments of Dr. Bastian. I turned to it with the anxious desire to 
learn whether the statements made concerning it were correct. 
The conditions laid down as to the strength of the solution, the temperature to be 
