138 INCREASE OF ANIMALCULES. 



everything living, and all germs in the flask or in 

 the tubes were destroyed, and all access was cut off 

 by the sulphuric acid on the one side, and by the 

 potash on the other. I placed this easily moved 

 apparatus before my window, where it was exposed 

 to the action of light, and also, as I performed my 

 experiments in the summer, to that of heat. At the 

 same time, I placed near it an open vessel with the 

 same substances that had been introduced into the 

 flask, and also after having subjected them to a 

 boiling temperature. In order now to renew con- 

 stantly the air within the flask, I sucked with my 

 mouth several times a day the open end of the 

 apparatus filled with solution of potash, by which 

 process the air entered my mouth from the flask 

 through the caustic liquid, and the atmospheric air 

 from without entered the flask through the sulphuric 

 acid. The air was of course not altered in its com- 

 position by passing through the sulphuric acid into 

 the flask, but if sufficient time was allowed for the 

 passage, all the portions of living matter, or of 

 matter capable of becoming animated, were taken 

 up by the sulphuric acid and destroyed. From the 

 28th of May, until the early part of August, I con- 

 tinued uninterruptedly the renewal of the air into the 

 flask, without being able, by the aid of the micro- 

 scope, to perceive any living animal or vegetable 

 substance, although during the whole of the time 

 I made my observations almost daily on the edge of 

 the liquid ; and when at last I separated the dif- 



