The Conditions of Infusorial Life. 97 



of M. Pasteur, which are highly instructive. He introduced the 

 same quantity of a fermentable liquid in several glass bulbs, 

 drew their necks out in a lamp, and twisted them in various 

 directions, but left them all open. In the greater number he 

 boiled the liquid for several minutes, leaving three or four in 

 which the heating: was not carried to ebullition. All were then 

 placed in a situation where the air was still. In from twenty- 

 four to forty-eight hours, the bulbs which had not been boiled, 

 but whose contents had experienced that temperature in pre- 

 paration, exhibited " divers mucors," and their liquor was 

 " troubled," while the fluid in the remainder remained limpid 

 for months. Upon these results M. Pasteur remarks, " All 

 the bulbs were open; without doubt it was the sinuosity and 

 inclination of their necks which protected their liquid contents 

 from the fall of atmospheric germs. Common air, it is true, 

 entered briskly at the beginning ; but at that time the liquid 

 was very hot, and slow to cool, so it caused all the germs con- 

 veyed by the air to perish; and afterwards, when the liquor 

 was cool enough to render possible the development of germs, 

 the air entering slowly allowed its dust to fall in the opening 

 of the neck, or on the walls of the entrance." Upon cutting 

 off the neck of one bulb, and placing the resulting aper- 

 ture vertically, mildews and bacteriums appeared in a few 

 days.* M. Pouchet attached importance to proving that com- 

 mon air did not abound in germs. M. Pasteur, in the interest 

 of the opposite party, demonstrated the same thing. He 

 took a number of glass bulbs partially filled with an infusion, 

 boiled them to produce a vacuum, and sealed up their necks. 

 These, on being broken in various situations, allowed air to 

 rush in, and were again sealed up. For the most part, the 

 liquor became cloudy after a few days, and the vessels exhibited 

 a greater variety of mucedines and torulacese than if they had 

 been freely exposed to the air. But it happened many times in 

 each series of trials that the fluid in some vessels remained as 

 unchanged as if it had received ' c calcined air," which M. Pasteur 

 asserts to be unproductive, in opposition to M. Pouchet. In the 

 course of these inquiries, air was obtained from various localities, 

 among others, at Montanvert, from the Glacier des Bois, and only 

 one of the vessels filled in that situation gave birth to a mucedine. 

 Thus we find the two classes of experimenters agreeing in 

 one conclusion, that the air does not contain that prodigious 

 quantity of noticeable germs that former microscopists imagined 

 to exist. Nor have observations been successful in discovering 

 enough germs to account for the appearance of animalcules of 

 the larger sort, which soon occurs under favourable conditions. 

 M. Pouchet has been at great pains to collect the particles which 

 * Comjotes Bendus, January to June, 1860, p. 303. 



