XI PHENOMENA OF ORGANIC NATURE 389 



taneous generation. He had succeeded in catching 

 the germs and developing organisms in the way 

 he had anticipated. 



It now struck him that the truth of his conclu- 

 sions might be demonstrated without all the appa- 

 ratus he had employed. To do this, he took some 

 decaying animal or vegetable substance, such as 

 urine, which is an extremely decomposable sub- 

 stance, 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 into an S shape or 

 zig-zag, leaving it open at the end. The infusion 

 then gave no trace of any appearance of spontaneous 

 generation, however long it might be left, as all 

 the germs in the air were deposited in the begin- 

 ning of the bent neck. He then cut the tube close 

 to the vessel, and allowed the ordinary air to have 

 free and direct access ; and the result of that was 

 the appearance of organisms in it, as soon as the 

 infusion had been allowed to stand long enough to 

 allow of the growth of those it received from the 

 air, which was about forty-eight hours. The re- 

 sult of M. Pasteur's experiments proved, therefore, 

 in the most conclusive manner, that all the appear- 

 ances of spontaneous generation arose from nothing 

 more than the deposition of the germs of organisms 

 which were constantly floating in the air. 



To this conclusion, however, the objection was 

 made, that if that were the cause, then the air 



