234 MICRO-ORGANISMS AND FERMENTATION. 



withstanding all these observations, the school of spontaneous 

 generation maintained their belief, and still numbered many 

 adherents. 



In 1857 Pasteur, the distinguished French scientist, entered 

 the field. He submitted the problem to such conclusive 

 experimental treatment, from every side, that his conclusions 

 were generally adopted, and have been held ever since. He 

 proved that the many unsuccessful experiments designed to- 

 overthrow the doctrine of spontaneous generation were 

 occasioned by the fact that the organic liquids concerned had 

 not been exposed to a sufficiently high temperature, or heated 

 for a sufficiently long period. Moreover, he showed that in 

 such cases the liquid under treatment was not so greatly 

 altered that it was no longer fit for the development of the 

 germs, as the supporters of spontaneous generation maintained. 

 Thus, if the liquid is boiled in a flask, the neck of which is 

 drawn out into a tube and twice bent (the same idea as that 

 of Hoffmann and Chevreul) so that the liquid remains sterile, 

 and if a small portion of the liquid is then allowed to run 

 into the tube, it soon begins to ferment, owing to the germs 

 deposited in the tube coming in contact with the liquid. The 

 same thing occurred when the air is passed through cotton- 

 wool and a small quantity of the wool is introduced into the 

 sterilised liquid. Pasteur also employed gun-cotton in place 

 of ordinary cotton-wool. Air passed through gun-cotton was 

 sterilised, and the fluid, after boiling sufficiently, remained 

 sterile for an unlimited time. The gun-cotton was afterwards 

 dissolved in alcohol and ether, and it was proved that it 

 contained the same microscopical organisms that develop in 

 liquids undergoing fermentation and putrefaction. 



This great work of Pasteur's resulted in the overthrow of 

 all proofs previously adduced on behalf of the school that 

 maintained the spontaneous generation of microscopical life 

 in organic liquids. He established the extremely important 

 result for industry which embodied all the essential principles 

 of the technique of sterilisation. A high stage of development 

 of this technique has since been reached, both in its purely 

 scientific and practical aspects. 



Thus was laid the foundation of the belief that fermenta- 



