182 THE FLOATING-MATTER OF THE AIR. 



one of cucumber, bore the ordeal uninjured. After 

 cooling, their sealed ends being broken off. they were 

 placed in the warm room. The melon remained per- 

 manently sterile, but in two days the cucumber-infusion 

 became turbid and laden with fatty scum. 



Eight similar bulbs were boiled on the same day for 

 five hours and a half. Four of them burst, but four 

 remained intact. Of these, two contained cucumber-, 

 one melon-, and one turnip-infusion. Three out of 

 the four bulbs were sterilized by the long-continued 

 boiling, but one cucumber-bulb passed through the 

 ordeal unscathed. Two days after the operation it 

 swarmed with life, and was covered with a fatty scum 

 formed of matted Bacteria. 



Many similar experiments were subsequently made. 

 On the 27 th of January, for example, six bulbs of 

 turnip-infusion were boiled for 220 minutes, six for 

 300 minutes, and two for 305 minutes. Suspended in 

 the air above each infusion was a sprig of old Colchester 

 hay, this being purposely introduced to augment the 

 chance of infection. Notwithstanding its presence the 

 bulbs were one and all permanently sterilized. The 

 specific gravity of the infusion was in all cases 1007. 



The sprigs of old hay were afterwards shaken into 

 the liquid, but they produced no effect. For weeks 

 afterwards the infusion remained clear. Was this im- 

 potence to generate life due to the fact that the nutri- 

 tive power of the infusion had been destroyed by the 

 'blighting influence of heat'? Not so; for when the 

 same infusion was infected by a sprig of fresh hay, by a 

 small pellet of cotton-wool rubbed against the dusty 

 shelves of the warm room, or by a speck of another 

 infusion containing Bacteria, it never failed to develop 

 life. The only observed difference between the effect 

 produced by the dry hay or dust and the living Bacteria 



