40 ORIGIN OF LOWEST ORGANISMS. 



of ebullition. Believing that the air is the source of 

 germs from which Life is first developed in infusions, 

 he thinks that what rapidly enters at first, on the 

 cessation of ebullition, has its germs destroyed by 

 contact with the almost boiling liquid ; whilst the air 

 which enters subsequently, and more slowly, is sup- 

 posed to deposit its germs in the various flexures of 

 the tubes, so that none are able to reach the fluid 

 itself. Infusions, thus protected, do not undergo putre- 

 faction, says M. Pasteur, because the access of pre- 

 existing living things is necessary for the initiation of 

 this change, and such access is prevented by the tor- 

 tuous and bent neck of the flask. 



Others say that some fluids submitted to the condi- 

 tions mentioned, will undergo putrefactive changes, 

 and that, therefore, these experiments of M. Pasteur 

 are utterly incapable of settling the general question 

 as to the cause of fermentation and putrefaction, and 

 also that concerning the origin of Life. Although 

 acknowledging a certain difficulty in explaining the 

 results which are sometimes attained by this method, 

 some of us would rather confess this than confidently 

 offer explanations as M. Pasteur did which may in 

 a short time be stultified by the results of other expe- 

 riments with different fluids. 



Having previously shown* that living things could 

 appear and multiply in such a flask as M. Pasteur 



* ' Nature,' 1870, No. 36, p. 193. 



