VITALITY OF PUTEEFACTIVE ORGANISMS. 133 



for five minutes, and afterwards placed permanently in 

 a warm room. 



The annexed woodcut (fig. 11), taken from the 

 ' Proceedings ' of the Eoyal Institution, shows a cham- 

 ber with its six test-tubes, its side windows w w, its 

 pipette c, and its bent tubes a b, which connect the air 

 of the chamber with the external air. 



In upwards of fifty chambers thus constructed, many 

 of them used more than once, it was, without excep- 

 tion, proved that a sterilized infusion in contact with 

 air shown to be self-cleansed by the luminous beam re- 

 mained sterile. Never, in a single unexplained instance, 

 did such an infusion show any signs of life. That the 

 observed sterility was not due to any lack of nutritive 

 power in the infusion, was proved by opening the back 

 door and permitting the uncleansed air to enter the 

 chamber. The contact of the floating matter with the 

 infusions was invariably followed by the development of 

 life. Numerous examples of these results were placed 

 before the Fellows of the Eoyal Society at their Meet- 

 ing on the 1 3th of January, 1876. 



Prior to the date here referred to, great public 

 interest had been excited, and, I may add, considerable 

 scientific uncertainty had been produced in reference 

 to this subject, both in England and America, by the 

 writings of Dr. Bastian. These writings consisted, in 

 part, of theoretic considerations and reflections, not 

 new, but sometimes very ably stated, based on the 

 general doctrine of Evolution; and, in part, of vei7 

 pungent criticisms of those who, though believers in 

 Evolution, declined to accept the writer's programme 



Cohn has inadvertently inferred that the infusions themselves were 

 raised above their boiling-points. The tubes being open, the tem- 

 perature of ebullition is of course independent of the source which 

 provokes it. 



