228 THE POPULAR SCIENCE MONTHLY. 



different fermentations may give rise to one or even several identical 

 products." 



From this statement of the physiological conditions that modify 

 the products of fermentation, it must be seen that uniformity in the 

 quality of ensilage can only be secured by preventing fermentation 

 altogether, or confining it within the narrowest possible limits. This 

 can only be done by killing the bacteria of fermentation in the ear- 

 liest stages of their activity, which would result in the production of 

 ensilage free from acidity, and closely resembling, in quality, the green 

 fodder from which it is made. If the bacteria can be killed, when the 

 silo is covered and weighted, the inclosed mass of ensilage will be 

 practically preserved under the same conditions as fruits, or vegeta- 

 bles, or meats, are preserved when canned. 



The practical question, then, presents itself as to how this can best 

 be accomplished. An extended series of observations on the samples 

 of ensilage from the experimental silo have already been made, to de- 

 termine the temperature required to kill the bacteria which cause the 

 acid fermentations. This will, undoubtedly, vary somewhat with the 

 kind of produce under treatment, and its condition when put in the 

 silo. Thus far my experiments seem to indicate that a temperature of 

 from 115° to 122*^, maintained for one or two hours, will be sufficient 

 to kill the bacteria under the conditions in which they are now placed. 

 In this connection attention must be called to the fact that the time of 

 exposure to a given temperature is quite as important as the tempera- 

 ture itself. A given temperature, continued for several days, may have 

 a better effect than a higher one maintained but a few minutes. Again, 

 a degree of heat that will kill the mature and active bacteria will not, 

 in all probability, kill the germs which may produce succeeding gen- 

 erations of active bacteria if the given temperature is continued but 

 a short time. 



From the results recorded in the table, it is reasonable to infer 

 that an initial temperature sufficiently high to kill the active bacteria 

 would be continued for several weeks, and this, in all probability, would 

 insure the destruction of any successive generations of bacteria that 

 might be produced from the germs that had not been killed. For 

 this purpose, silos with walls of wood may have an important advan- 

 tage over those constructed of materials that are better conductors of 

 heat. 



In filling the silo, all writers on ensilage agree in giving directions 

 which are based on Liebig's chemical theory of fermentation. The 

 thorough packing of the ensilage as it is put in and the rapid filling 

 of the silo are points that are strongly urged to prevent, as far as pos- 

 sible, the exposure of the fodder to the oxygen of the atmosphere, 

 which is assumed to be the exciting cause of fermentation. In the 

 light of the physiological theory of fermentation it will, however, be 

 readily seen that the living ferments, which produce acidity, are 



