SOLUTIONS FREE FROM DUST 100 



home. The other two flasks had no stopper, and 

 the mouth of each was exactly half an inch in 

 diameter, and was left freely open for dust to drop 

 in; and yet, after the expiration of three months, 

 the fluid in these two flasks (though diminished 

 by evaporation) remained perfectly clear, like that 

 in the two-stoppered flasks by the side of which 

 they were standing. 



A microscopical examination of some of the 

 flakes of silica in each, moreover, showed just the 

 same kind of Torula? and Bacteria; and they were 

 not more notably plentiful in that taken from the 

 open than in that from the closed flasks, nor were 

 any different organisms found in the former. 



This trial was made with a solution of a kind 

 which I had previously found to yield organisms 

 readily (after it had been boiled for ten minutes) 

 in the course of three or four weeks; so my con- 

 clusion was that in each of the four flasks organ- 

 isms had been engendered de novo, and that 

 multiplication had not taken place more freely in 

 those that were open than in those that had re- 

 mained closed. Again, after another period of 

 three months, the fluid in each flask was found to 

 be still quite clear and unclouded. 



Yet I had previously found that when the same 



