PEESISTENCE OF PUTEEF ACTIVE AND INFECTIVE OEGANISMS. 
197 
It will be remembered that when the infusion and the air above it possessed their ordi- 
nary supply of oxygen, 180 minutes’ boiling failed to sterilize the turnip-infusion. Here, 
when the air was withdrawn from the liquid, exposure for one eighteenth of the fore- 
going interval sufficed to produce perfect barrenness. The infusion in the three bulbs 
here operated on remains to the present hour clear in body and perfectly free from scum. 
On the 15th of March seven bulbs charged with infusion of turnip were treated in 
the manner just described, being purged of their air by three hours’ action of the 
Sprengel pump, and boiled for ten minutes afterwards. Six out of the seven remain 
perfectly pellucid. 
On the 16th of March the result was still further verified. Seven bulbs were then 
charged with turnip-infusion, exhausted first by the air-pump, and afterwards by five 
hours’ action of the Sprengel pump. Hermetically sealed and boiled as before, six out 
of the seven remain as clear as distilled water. 
On the 20th of March seven bulbs were charged with infusion of cucumber, and sub- 
jected to the action of the Sprengel pump for seven hours. They were afterwards 
treated in the manner just described. They were all completely sterilized. 
On the 27th of March three bulbs were charged with cucumber-infusion and subjected 
to the action of the Sprengel pump for five hours. One of them was subsequently boiled 
for five minutes, another for one minute, while the third was left unboiled. This third 
tube became faintly cloudy, but the two others remain perfectly free from life. 
This result invited repetition. On the 29th accordingly six bulbs of cucumber-infu- 
sion were exhausted for five hours, and afterwards sealed and boiled for a single minute. 
Five of the six bulbs remained permanently clear ; one became cloudy. 
On the 30th of March six bulbs containing turnip-infusion were exhausted for five 
hours and boiled afterwards for a minute. Five remain perfectly clear, one has become 
muddy. 
On the 6th of April five bulbs of beef-infusion were subjected for three hours to the 
action of the Sprengel pump and boiled for a minute afterwards. They all remain 
brilliant. 
On the 7th of April five bulbs of mutton-infusion were treated like the beef-bulbs, 
being exhausted for three hours and boiled for a minute. All remain clear. This 
experiment was repeated and confirmed on the 20th of April. 
On the 14th of April three bulbs of pork-infusion were exhausted for four hours and 
boiled for a minute. They all remain pellucid. 
On the 17th of April four bulbs of accurately neutralized urine were exhausted for 
five hours and boiled for a minute. Three of them remain bright ; one has become cloudy. 
This does not exhaust the list of instances. Many other infusions have been sterilized 
by this method since the 17th of April. 
It is perfectly certain that in most, if not all, of these cases 200 minutes’ boiling would 
have proved insufficient to sterilize the infusion if it had been supplied with air. 
Here the question naturally arises : — What would happen if the bulbs were exhausted 
mdccclxxvii. 2 p 
