74 THE FLOATINa-MATTER OF THE AIR. 



phenomena of spontaneous generation. I would there- 

 fore recall to mind what has been stated on a previous 

 page, that in most of the experiments here described 

 the infusion at starting was strong, and that it was 

 permitted to evaporate with extreme slowness until its 

 concentration became three or four fold what it had 

 been at starting. Every experiment was thus converted 

 into an indefinite number of experiments on infusions 

 of different strengths. Never, in my opinion, was the 

 requirement as to concentration more completely ful- 

 filled, and never was the reply of Nature to experiment 

 more definite and satisfactory. The temperatures, 

 moreover, to which the infusions have been sub- 

 jected embrace those hitherto alleged to be effectual, 

 extending indeed beyond them in both directions.^ 

 They reached from a lower limit of 50° to a higher 

 limit of more than 100° Fahr. Still higher tempera- 

 tures were applied in other experiments to be described 

 subsequently. With regard to the number of the 

 infusions, more than fifty moteless chambers, each with 

 its system of tubes, have been tested. There is no 

 shade of uncertainty in any of the results. In every 

 instance we have, within the chamber, perfect limpidity 

 and sweetness — without the chamber, putridity and its 

 characteristic smells. In no instance is the least counte- 

 nance 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 

 whatever to generate life anew. 



If it should be asked how I have assured myself 

 that the protected liquids do not contain Bacteria, I 

 would, in the first place, reply that with the most 

 careful microscopic search I have been unable to find 



* See Proc. of Roy. Soc. vol. xxi. p. 130, where a temperature of 

 70° is described as effectual. 



