64 THE FLOATING-MATTER OF THE AIR. 



Six other tubes charged with the same infusion, 

 "boiled in the same way, became turbid in a few days, 

 and subsequently covered with thick layers of PenicU- 

 lium. 



§ 8. Hay-Infusion, 



This infusion has been credited with a power of 

 spontaneous generation similar to that ascribed to 

 turnip-juice. The hay being chopped into short lengths 

 was digested for four hours in water kept at a tempera- 

 ture of 120° Fahr. On the 24th of September the 

 filtered infusion was introduced into its chamber, and 

 boiled there for five minutes. Six tubes were charged 

 with the protected liquid, while six other tubes, filled 

 with the same infusion, were placed on a stand outside 

 the case. 



On the 27th the inside flasks were clear, the outside 

 ones faintly turbid. On the 28th spots of mould ap- 

 peared upon all the exposed surfaces. The infusion in 

 one of the outside tubes had been diluted with distilled 

 water, and in it the development of life was far more 

 rapid than in the five others ; all of them, however, on 

 the 28th contained Bacteria. 



On the 29th I noticed a larger organism than the 

 Bacteria moving rapidly to and fro across the field, the 

 drop containing it being taken from the dilute infusion. 

 Several of these monads were seen upon the 30th gambol- 

 ling among the smaller Bacteria, appearing bright or 

 dark as they sank or rose in the liquid, a film of which, 

 large as they looked, was to them an ocean. Swarms of 

 Bacteria were seen on the 2nd of October, their transla- 

 tory motions being so rapid and varied, and so apparently 

 guided by a purpose, as to render it difiicult to believe 

 that they could be anything else than animals. On the 

 15th there was a marvellous exhibition of the larger 



