SPONTANEOUS GENERATION. 295 



contact with either animal or vegetable life. I stand 

 carefully to leeward of the flasks, for no dust or particle 

 from my clothes or body must be blown towards them. 

 An assistant ignites the spirit-lamp, into the flame of 

 which I plunge the pliers, thereby destroying all attached 

 germs or organisms. Then I snip off the sealed end 

 of the flask. Prior to every snipping the same process 

 is gone through, no flask being opened without the 

 previous cleansing of the pliers by the flame. In this 

 way we charge our seven-and-twenty flasks with clean 

 vivifying mountain air. 



We place the fifty flasks, with their necks open, 

 over a kitchen stove, in a temperature varying from 

 50° to 90° Fahr., and in three days find twenty-one out 

 of the twenty-three flasks opened on the hayloft invaded 

 by organisms — two only of the group remaining free 

 from them. After three weeks' exposure to precisely 

 the same conditions, not one of the twenty-seven flasks 

 opened in free air had given way. No germ from the 

 kitchen air had ascended the narrow necks, the flasks 

 being shaped so as to avoid this contingency. They 

 are still in the Alps, as clear, I doubt not, and as free 

 from life as they were when sent off from London.' 



What is my colleague's conclusion from the experi- 

 ment before us? Twenty-seven putrescible infusions, 

 first in vacuo, and afterwards supplied with the most 

 invigorating air, have shown no sign of putrefaction 

 or of life. And as to the others, I almost shrink from 

 asking him whether the hayloft has rendered them 

 spontaneously generative. Is not the inference here 

 imperative that it is not the air of the loft — which is 

 connected through a constantly open door with the 

 general atmosphere — ^but something contained in the 



* An actual experiment made at the Bel Alp is here described. 



