32 THE FLOATING-MATTER OF THE AIR. 



even after this interval no fungi appeared. In a second 

 series of experiments there was a similar exception. In 

 a third series the cork stoppers used in the first and 

 second series were abandoned, and glass stoppers em- 

 ployed. Flasks containing decoctions of tea, beef, and 

 hay were filled with common air, and other flasks with 

 sifted air. In every one of the former fungi appeared 

 and in not one of the latter. These experiments 

 simply ruin the doctrine that Dr. Bennett finally 

 espouses. 



In all these negative cases, the air was forced through 

 the bent tubes and bulb into the boiling-hot infusion. Dr. 

 Bennett made a fourth series of experiments, in which, 

 previous to forcing in the air, he permitted the flasks 

 to cool. Into four bottles thus treated he forced pre- 

 pared air, and after a time found fungi in all of them. 

 What is his conclusion? Not that the boiling-hot 

 liquid, employed in his first experiments, had destroyed 

 such germs as had run the gauntlet of his apparatus ; 

 but that air^ which, previous_ to being sealed up, had 

 been exposed to a temperature of 212°, is too rare to 

 support life. This conclusion is so remarkable that it 

 ought to be stated in Dr. Bennett's own words. ' It 

 may be easily conceived that air subjected to a boiling, 

 temperature is so expanded as scarcely to merit the 

 name of air, and that it is more or less unfit for the pur- 

 pose of sustaining animal or vegetable life.' 



Numerical data are attainable here, but they are 

 unnecessary. As a matter of fact, I live and flourish 

 for a considerable portion of each year in a medium of 

 less density than that which Dr. Bennett describes as 

 scarcely meriting the name of air. The inhabitants of 

 the higher Alpine chalets, with their flocks and herds, 

 and the grasses which support these, do the same ; 

 while the chamois rears its kids in air rarer still. 



