168 THE FLOATING-MATTER OF THE AIR. 



worn in the laboratory and to dress himself in others. 

 The infusions prepared under these conditions were 

 cucumber, melon, turnip, and artichoke, which, from 

 beginning to end, were operated on below stairs. Two 

 chambers were devoted to each infusion, and after the 

 usual boiling in the chanabers they were permitted to 

 remain in the store-room throughout the night, being 

 transferred to the warm laboratory next morning. 



I fully expected that the majority of these chambers 

 would prove sterile. I did not expect to find them all 

 in this condition, because the chambers had been put 

 together in the laboratory, the air of which must liave 

 deposited its germs not only on the glycerine-coated 

 interior of the chambers, but also on the inner surfaces 

 of the testr-tubes. My expectation, moderate as it was, 

 was not realized. The only noticeable peculiarity in 

 the deportment of the infusions was that they yielded 

 tardily, but in the end every one of them, without 

 exception, broke down. 



Was the infection in this case derived from the air 

 of the store room ? I tliink not ; and for this reason : — 

 On the 27th of December four hermetically-sealed flasks, 

 charged with a cucumber-infusion which had remained 

 perfectly pellucid for some weeks, were opened in the 

 store-room ; four similar flasks, charged with the same 

 infusion, were opened at the same time in the laboratory. 

 On the 31st of December the whole group of the latter 

 four was found invaded by organisms, while those 

 opened in the store-room contracted no infection and 

 developed no life. 1 do not imagine, therefore, that the 

 air of the store-room had anything to do with the con- 

 tamination of the infusions contained in the closed cham- 

 bers, but conclude that the contagium already existed 

 in the chambers wheu they were taken down stairs. 

 'J'hey acted as infected houses placed in salubrious air. 



