3O4 AGRICULTURAL BACTERIOLOGY. 



take place in the protoplasm of the plant cells before their 

 death. They find that the acid will develop normally in silage 

 in the presence of ether, and hence it is not due to bacteria. 

 They find, moreover, that the amount of acid developed is 

 roughly proportional to the length of time which elapses be- 

 tween the packing of the silo and the final death of the 

 plant cells. When silage is made from immature corn, the 

 cells are more active and remain alive considerably longer than 

 they do when made from fully ripened corn, and under these 

 conditions the amount of acid developed in the silage is greater. 

 Thus all of the general changes occurring in silage are at- 

 tributed to the activities of the protoplasm of the plant cells, as 

 they are slowly dying under the conditions which exist in the 

 silo. The chief fermentations in silage are therefore not due 

 to the action of bacteria. 



The development of the flavor in the silage is as yet not 

 understood. Neither the respiratory changes, nor the changes 

 in the protoplasm mentioned, are such as are likely to give rise 

 to flavor. To what the flavors are due the authors we have re- 

 ferred to are unable to say. They are inclined to believe them 

 due to the action of certain enzymes which they think are lib- 

 erated from the plant cells when dying. That such enzymes 

 may be thus liberated from plant cells we have already noticed 

 in tobacco, but that they produce the flavors found has not 

 yet been certainly proved, or even rendered probable. In re- 

 gard to this phase of the silage fermentation we are therefore 

 in almost absolute ignorance, and cannot as yet say whether 

 it is wholly produced by chemical enzymes or whether micro- 

 organisms may not have something to do with it. 



From all these facts it becomes clear that while this method 

 of preparing food is due to a fermentation it cannot be attrib- 

 uted to the growth of microorganisms. It certainly involves 

 some other factors, and it is uncertain whether bacteria, or 

 other microorganisms have anything to do with the process as 



