The Conditions of Infusorial Life. 95 



found the liquid clear till the twentieth day, when it became 

 cloudy. Four days later- he discovered a little blue spot, which 

 was the first appearance of the fungus Penicillium glaucum. 

 This plant increased, vibrions appeared, and likewise monads 

 of indeterminable species. The repetition of Schwann's ex- 

 periments produced a similar result. Messrs. Joly and Musset 

 give an account of similar experiments in the Com/ptes Rendus,* 

 in which they say they have vainly submitted the organic 

 substances employed to prolonged ebullition, in vain submitted 

 the air to a very elevated temperature in tubes brought to a 

 white red heat (rouge blanc) , or passed it through sulphuric acid; 

 in all cases they found very simple organic substances developed 

 in their infusions. It may be well to mention at this point the 

 observations of M. Pasteur, who has shown that the spores of 

 mildews are not destroyed by being exposed to the action of con- 

 centrated sulphuric acid for several days. Other germs of objects 

 of low organization may be equally difficult to kill. 



It was considered by M. Pouchet that if the air contained 

 the supply of germs usually imputed to it, and ready for depo- 

 sition in a suitable liquid, the first washings of the air ought to 

 contain the largest number, and subsequent washings would 

 exhibit a marked diminution. To test this, he took eight of 

 Wolffs bottles, and partially filled them with a decoction of 

 hay, which had been boiled for an hour, filtered, and introduced 

 boiling hot into the vessels. After this he passed steam through 

 the series of bottles for half an hour. They were then left for 

 fifteen days, when every vessel exhibited a population of kolpods, 

 the last of the series being as rich as those preceding it. 

 During two years he frequently repeated these experiments, 

 with various contrivances to facilitate the stoppage of any par- 

 ticles the air contained, and he arrived at the conclusion that 

 ' ' the animalcules were, normally, equally numerous in all the 

 vessels — in the first as in the last.-" In one case, however, he 

 had the curious fortune to find the first vessel solely occupied 

 with Navicula obtusa and a green conferva ; the second chiefly 

 with Dileptus folium; the third with small animalcules and 

 several rotifers; the fourth with the same conferva as in the 

 first, and some kolpods; the fifth exhibited vorticella?, epistylis, 

 and glaucomse, while other objects had been developed in the 

 sixth and seventh. During this experiment a large measure of 

 ah- was daily blown through the series of bottles. Upon this 

 M. Pouchet remarks, that while the results are inexplicable 

 upon the germ theory, they are easily explained by hetero- 

 genesis, as ' ' each vessel has engendered special generations, 

 because it was the seat of particular modifications, which time had 

 diffused unequally through the macerations.-''' The "unequal 



* 21st January, 1861. 



