SILOS, ENSILAGE AHD SILAGE. 41 



agent in the changes taking place in all processes of fer- 

 mentation and decay. What are now known to be the 

 essential factors of fermentation and putrefaction were 

 entirely ignored by Liebig ; and yet his theories were 

 unquestioned for many years, and even now their influ- 

 ence is apparent in the popular literature of agricultural 

 science, notwithstanding the repeated disproof of the 

 assumptions on which the theory was based, by the 

 results of direct experiments, beginning in 1838 and 

 continued to the present time. 



More than twenty-five years ago, Pasteur verified the 

 results obtained by previous investigations, and supple- 

 mented the work by a masterly series of researches 

 which proved conclusively that fermentation was a 

 biological process, the result of the vital activities of 

 living organisms. 



If real progress is made in our knowledge of the com- 

 plex changes involved in the ensilage of green fodder, 

 the biological theory of fermentation, which can no 

 longer be consistently questioned, must be accepted as 

 the only safe guide in experimentation, and the obsolete 

 theories of Liebig, that were based on assumed data, 

 must be entirely discarded. 



A brief historical summary of the progress of discovery 

 will enable us to form a correct estimate of the present 

 conditions of science relating to the subject, and lead to 

 a recognition of the real significance of the biological 

 factors of fermentation. 



Iii 1680 the Dutch naturalist, Leuwenhoek, with 

 lenses made by himself, examined yeast and found it 

 was composed of minute granules, the real nature of 

 which he was unable to determine. 



Fabroni, of Florence, in 1787 again noticed the gran- 

 ules of yeast, which he looked upon as a "vegeto-ani- 

 mal" substance, and a further step in advance was made 

 by Astier in 1813, who claimed that the yeast granules 



