SP ONTA NE US GENERA TI ON. 



593 



without further precaution, every one of the tubes would putrefy and 

 till itself with life. The liquid has been in contact with dust-laden 

 air by which it has been infected, and the infection must be destroyed. 

 This is done by plunging the six 

 tubes into a bath of heated oil and 

 boiling the infusion. The time re- 

 quisite to destroy the infection de- 

 pends wholly upon its nature. Two 

 minutes' boiling suffices to destroy 

 some contagia, whereas two hun- 

 dred minutes' boiling fails to de- 

 stroy others. After the infusion 

 has been sterilized, the oil-bath is 

 withdrawn, and the liquid, whose 

 putrescibility has been in no way 

 affected by the boiling, is aban- 

 doned to the air of the chamber. 



With such chambers I tested, 

 in the autumn and winter of 1875- 

 '76, infusions of the most various 

 kinds, embracing natural animal 

 liquids, the flesh and viscera of 

 domestic animals, game, fish, and 

 vegetables. More than fifty mote- 

 less chambers, each with its series 

 of infusions, were then 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 lim- 

 pidity 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 mat- 

 ter, has any power whatever to generate life anew. 



Remembering, then, the number and variety of the infusions em- 

 ployed, and the strictness of our adherence to the rules of preparation 

 laid down by the heterogenists 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 at least 500 chances have been given to it, 

 but it has nowhere appeared 



The argument is now to be closed and 



vol. xii. 38 



