58 SILOS, ENSILAGE AND SILAGE. 



fermentation may then be considered under two distinct 

 heads : 1st, the zymases, or so-called soluble ferments, 

 which are elaborated in the exercise of the normal 

 functional activity of the living cells of the tissues. 

 They "invert" cane sugar and convert it into glucose, 

 change starch into sugar, or like the pancreatic secre- 

 tion, change insoluble proteids into soluble and diffusi- 

 ble peptones, or in general terms they may be said to 

 bring about those changes which facilitate the transfer 

 and assimilation of food materials, and according to 

 Dumas, they "always sacrifice themselves in the exer- 

 cise of their activity." They do not act like the true 

 ferments, and they must be looked upon as essential fac- 

 tors in the physiological activities of both plants and 

 animals. 



3d, The true ferments, which, on the other hand, are 

 living organisms that increase and grow at the expense 

 of the substances fermented, and produce fermentation 

 as an incident of their vital processes. 



Pasteur defines the true fermentations as physiological 

 activities, " the direct consequence of the processes of 

 nutrition, assimilation and life, when they are carried 

 on without the agency of free oxygen," or, "as a result 

 of life without air." The true ferments may be divided 

 into two groups : 



1st, The saccharomyces, or budding fungi, of which 

 beer yeast may be taken as the type. They are real 

 microscopic plants that multiply by budding, and have 

 likewise a process of reproduction by spores. The 

 prominent members of this group are alcoholic ferments. 



#d, The so-called schizomycetes, or fission fungi, that 

 are perhaps better called microbes, or bacteria.* 



*De Bary, an acknowledged authority on these lower forms of life, says the 

 members of this group are not properly fungi, and he prefers to call them Bac- 

 teria. He would likewise avoid the use of the term Bacterium as a generic name. 

 If, however, Bacterium is retained as the name of a genus, the group will be bet- 

 ter designated by the general term Microbes. 



