ORIGINATION OF LIVING BEINGS. 79 



been floating about in the air and had got caged in 

 this way. 



He went farther, and said to himself, "If these 

 really are the things that give rise to the appearance 

 of spontaneous generation, I ought to be able to take 

 a ball of this dusted gun-cotton and put it into one of 

 my vessels, containing that boiled infusion which has 

 been kept away from the air, and in which no in- 

 fusoria are at present developed, and then, if I am 

 right, the introduction of this gun-cotton will give rise 

 to organisms." 



Accordingly, he took one of these vessels of in- 

 fusion, which had been kept eighteen months, without 

 the least appearance of life in it, and by a most inge- 

 nious contrivance, he managed to break it open and 

 introduce such a ball of gun-cotton, without allowing 

 the infusion or the cotton ball to come into contact 

 with any air but that which had been subjected to a 

 red heat, and in twenty-four hours he had the satis- 

 faction of finding all the indications of what had been 

 hitherto called spontaneous generation. He had suc- 

 ceeded in catching the germs and developing organisms 

 in the way he had anticipated. 



It now struck him that the truth of his conclusions 

 might be demonstrated without all the apparatus he 

 had employed. To do this, he took some decaying 

 animal or vegetable substance, such as urine, which 

 is an extremely decomposable substance, or the juice 

 of yeast, or perhaps some other artificial preparation, 

 and filled a vessel having a long tubular neck, with 

 it. He then boiled the liquid and bent that long neck 



