VITALITY OF PUTKEFACTIVE ORGANISMS. 181 



minutes. Six other bulbs, charged with the same in- 

 fusion and treated in the same way, were boiled for 

 30 minutes. Finally eight bulbs, similarly charged, 

 were boiled for 120 minutes. 



On the 23rd of December three of the first group of 

 bulbs, three of the second, and five of the third, had 

 their sealed ends filed off, and were afterwards exposed 

 to a tolerably constant temperature of about 90° Fahr. 

 Not one of these twenty bulbs preserved itself free from 

 life. On the 25th of December every one of them had 

 given way to cloudiness and turbidity. 



There was, however, a marked difference between 

 the sealed and the unsealed bulbs. To the latter, it 

 will be remembered, the air had access through the 

 plug of cotton-wool, while to the former no air had 

 access, save the small quantity imprisoned above the 

 infusion when the necks of the bulbs were sealed. The 

 aerated bulbs grew rapidly and thickly turbid, while a 

 passing cloudiness was all that showed itself in the 

 sealed ones. This soon disappeared, and left the in- 

 fusions apparently intact. In fact it required some 

 attention to detect the appearance of this fugitive life, 

 which existed only so long as there was oxygen to sus- 

 tain it. I have ranged the sealed and unsealed tubes 

 side by side in groups. To the most cursory observa- 

 tion the difference between them is obvious. The ex- 

 periment strikingly illustrates the dependence of the 

 special organisms here implicated on the oxygen of the 

 air. 



The experiments were pushed still further on the 

 28th of December. Two bulbs of cucumber, two of 

 melon, two of turnip, and two of artichoke were then 

 plugged, sealed, and maintained at the boiling tem- 

 perature for four hours. Six of the eight bulbs burst in 

 the operation, but two of them, a bulb of melon and 



