134 THE FLOATING-MATTER OF THE AIR. 



of its operations.* Passing over both theory and 

 criticism, I thought it wise to fix upon certain well 

 defined statements of fact which lay at the basis of the 

 weighty superstructure raised by their author, and to 

 bring these statements to the test of strict experiment. 



Thus it was affirmed ' that boiled tm-nip or hay- 

 infusions exposed to ordinary air, exposed to filtered 

 air, to calcined air, or shut off altogether from contact 

 with air, are more or less prone to swarm with Bacteria 

 and Vib^'iones in the course of from two to six days.' ^ 

 I resorted accordingly to filtered air, calcined air, and 

 to infusions withdrawn from air, but failed to discover 

 the alleged ' proneness ' to run into living forms. It 

 had also been affirmed that infusions of muscle, kidney, 

 or liver, placed ' in a flask whose neck is drawn out and 

 narrowed in the blowpipe flame, boiled, sealed during 

 ebullition, and kejDt in a warm place, swarmed after a 

 variable time with Bacteria and allied organisms.' ^ I 

 resorted to such flasks, employing infusions of fish, flesh, 

 fowl, and viscera, and on the 13th of January was able 

 to place before the Eoyal Society one hundred and 

 thirty flasks, every one of which negatived the fore- 

 going statement. 



Two objections were subsequently urged against 

 these results. The infusions, it was contended, were 

 not sufficiently concentrated, nor were the temperatures 

 sufficiently high. Both these objections were met by 

 the statement that forty-eight hours' exposure under 

 the same circumstances to common air sufficed to fill 

 these same infusions with life. Beyond this, however, 

 I was able to show that the temperatures employed by 

 me were exactly those which had previously been found 



' See ' Evolution, or the Origin of Life,' pp. 1C8, 169. 



2 'Evolution,' p. 94. 



» Transactions of the Pathological Society, 1875, p. 272. 



