DISTRIBUTION OF GERMS IN THE AIR 101 



air which has been heated or filtered through cotton. 



There are those exceptions which haunted the mind of 



jlelmholtz, of Schroeder. and Ihisciu and made them 



admit that there were some ' decompositions of organic 

 matter which needed only the presence of oxygen to 

 start them/ that is to say that spontaneous generation 

 was alone capable of explaining. Very well, there again 

 spontaneous generation has nothing to do with it. 

 Only carry up to 110 C. your milk, your yolk of egg, 

 your meat, and you will preserve them intact as easily 

 as the bouillon. The milk needs to be heated a little 

 more, and that is all there is to it. It is not that it 

 contains more resistant germs, but that it is slightly 

 alkalin, and in an alkalin medium germs are more resist- 

 ant to the action of heat. The proof is that a decoction 

 of yeast, which is easily sterilized by a short boiling at 

 100 C. when it is slightly acid, needs to be heated to 

 105 C. or 110 C. when there is added to it a small 

 amount of carbonate of lime. It behaves then like the 

 milk." 



We shall see later that there is in the interpretation of 

 this experiment an error brought to light by Bastian, 

 but which did not invalidate the conclusion, for Pasteur, 

 when he was deceived, had the art of never being deceived 

 more than half way. He approached the mark, when he 

 did not hit the bull's-eye. We shall find a new example of 

 this in the complementary demonstration which follows. 



VI 

 DISTRIBUTION OF GERMS IN THE AIR 



There was in favor of spontaneous generation one last 

 argument to which Pasteur had not yet replied. It is 

 the experiment to which we have referred, in which Gay- 



