ATMOSPHERE IK RELATION TO PUTREFACTION AND INFECTION. 
37 
Up to the present time the infusion in every tube of the six remains as clear as it was 
on the day of its introduction. 
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 Penicillium. 
§ 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 temperature 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 appeared upon all the exposed surfaces. The infusion in one of 
the 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 
them were seen upon the 30th gambolling 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 translatory 
motions being so rapid and varied, and guided by so apparent a purpose, as to render it 
difficult to believe that they could be any thing else than animals. On the 15th there 
was a marvellous exhibition of the larger Infusoria, which appeared to have driven the 
Bacteria from their habitat, as few of them were to be seen. My inability to find the 
larger creatures a second time in such numbers perplexed me, causing' me to conclude 
that I had accidentally alighted upon a colony of them. Subsequent experience with 
the pipettes already described pointed, however, to another source. 
While three days sufficed to break down the purity, and to fill with Bacterial life, the 
six exposed tubes, the six protected ones remained for more than three months as clear and 
healthy as they were on the day the infusion was poured into them. Neither a trace of 
mould upon the surface of any one of them, nor a trace of turbidity in its mass, was to 
be seen. 
Into another case containing three test-tubes a very strong infusion of hay was intro- 
duced on the 1st of October. It was boiled for five minutes, and then abandoned to the air 
of the case. Three other tubes exposed to the laboratory air were placed on a stand beside 
the case. The colour of the infusion was very deep, but it was quite transparent. One 
of the outer tubes was diluted with distilled water. On the 3rd the infusion in this tube 
was turbid, the others remaining clear. The germinal matter had in some way or other 
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