PERSISTENCE OE PUTREFACTIVE AND INFECTIVE ORGANISMS. 
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In the great majority of these experiments the deportment of alkalized hay-infusion 
contradicts that observed by Dr. Roberts and Professor Cohn. 
Six other pipette-bulbs, with their necks so bent and plugged with cotton-wool 
and asbestos that no impurity falling from the plug could reach the infusion, were 
also charged on the 2nd of October. Three of the bulbs, with their necks herme- 
tically sealed, were maintained for ten minutes at the temperature of boiling water, 
the sealed ends being afterwards broken off. The three other bulbs were boiled in an 
oil-bath, and had their necks plugged before ebullition ceased. All six bulbs have 
remained perfectly transparent up to the present time. 
Here , again, we have discordance between my results and those of Dr. Roberts and 
Professor Cohn. 
But on the 6th of October another infusion was prepared and neutralized, exactly 
in the same fashion as before. Five pipette-bulbs were charged with it ; they were 
hermetically sealed and immersed for ten minutes in boiling water. The sealed ends 
were afterwards broken off, and the bulbs exposed to a temperature of 90° Fahr. On 
the morning of the 8th of October (that is to say, two days after their preparation) 
the infusion in every one of the bulbs was turbid and covered with scum. 
Here once more we have perfect harmony between my results and those of Dr. Roberts 
and Professor Cohn. 
Reverting to the 2nd of October, fourteen of our ordinary small retort-flasks with bent 
necks (shown in fig. 4) were then charged with the neutralized hay- 
infusion. They were boiled for three minutes, and hermetically sealed 
whilst boiling. Some days afterwards one tube of the entire number 
was observed to have become lighter in colour and sensibly cloudy ; 
but thirteen out of the fourteen remained unchanged in colour, 
brightly transparent, and entirely free from life. 
Here the dissidence between my results and those of Professor Cohn, 
who also experimented with hermetically sealed flasks , reappears. 
Numerous other experiments with pipette-bulbs and retort-flasks 
were made at the time here referred to, but it is unnecessary to record them. Suffice 
it to say that, like those just described, some of them corroborated and some of them 
contradicted the results of Dr. Roberts and Professor Cohn. 
§ 4. Hay-infusions. Experiments with Cohn’s Tubes, 
For reasons given by himself*, Professor Cohn deviated from the method of experi- 
ment pursued by Dr. Roberts, employing, instead of the pipette-bulbs, flasks, the nature 
of which will be understood from the following description. Let a zone of a common 
test-tube, about one third of its length from its open end, be softened by heat, and let 
the softened glass be drawn out so as to form a tube of much narrower bore than the 
original test-tube. Thus modified, the tube would consist of an elongated bulb below 
* Beitrage, July 1876, p. 256. 
