SPONTANEOUS GENKEATION. 301 



requisite to destroy the infection depends wholly upon 

 its nature. Two minutes' boiling suffices to destroy some 

 contagia, whereas two hundred minutes' boiling fails to 

 destroy others. After the infusion has been sterilized 

 the oil-bath is withdrawn, and the liquid, whose putre- 

 scibility has been in no way affected by the boiling, is 

 abandoned to the air of the chamber. 



With such chambers I tested, in the autumn and 

 winter of 1875-6, infusions of the most various kinds, 

 embracing natural animal liquids, the flesh and viscera 

 of domestic animals, game, fish, and vegetables. More 

 than fifty chambers, each with its series of infusions, 

 were tested, many of them repeatedly. There was no 

 shade of uncertainty in any of the results. In every 

 instance we had, within the chamber, perfect limpidity 

 and sweetness, which in some cases lasted for more than 

 a year — without the chamber, with the same infusion, 

 putridity and its characteristic smells. In no instance 

 was the least countenance lent to the notion that an 

 infusion deprived by heat of its inherent life, and placed 

 in contact with air cleansed of its visibly suspended 

 matter, has any power to generate life anew. 



Kemembering then the number and variety of the 

 infusions employed, and the strictness of our adherence 

 to the rules of preparation laid down by the hetero- 

 genists themselves ; remembering that we have operated 

 upon the very substances recommended by them as 

 capable of furnishing, even in untrained hands, easy and 

 decisive proofs of spontaneous generation, and that we 

 have added to their substances many others of our own 

 — if this pretended generative power were a reality, 

 surely it must have manifested itself somewhere. 

 Speaking roundly, I should say that in such closed 

 chambers at least five hundred chances have been given 

 to it, but it has nowhere appeared. 



