SILOS, ENSILAGE AND SILAGE. 91 



top of the silo from the settling of the silage could not 

 be filled with fresh fodder without taking off, and replac- 

 ing, the heavily weighted cover, which involved a con- 

 siderable expenditure of labor. In the improved method 

 of filling, the settling of the silage, favored by the high 

 temperature, goes on gradually and continuously, as the 

 fodder is put in, and there is nothing to prevent succes- 

 sive additions of fresh fodder until the silo is completely 

 filled. 



It will be seen that all details of the slow filling pro- 

 cess are managed to favor the development of a tempera- 

 ture of at least 122 in all parts of the silo, to keep in 

 check, or diminish, the activity of the bacteria of the 

 acid fermentations. 



The cause of the temperature developed in the silage 

 has not been definitely ascertained, but from the facts 

 presented in the chapter on Fermentation, it may, with 

 apparent good reasons, be attributed to the normal 

 activities of the living plant cells in the maturation of 

 their contents. There is, at least, no evidence that it is 

 caused by a true fermentation, or by any direct process 

 of oxidation. There is, likewise, no evidence to warrant 

 the assumption that the high temperature involves a 

 direct loss of nutritive materials, as it is well known 

 that heat is evolved in the normal metabolism of plant 

 cells in the elaboration of organic substances. That the 

 metabolism of the cells of maize goes on after the plant 

 is cut up, is shown in the maturation of the grain in the 

 ear while attached to the stalks that are cut up before 

 the ears are glazed, and we cannot doubt that heat is 

 liberated in this process. This metabolism of the cells 

 must continue, in the presence of sufficient moisture, as 

 long as they retain their vitality. 



It must be admitted that the chemical changes taking 

 place in the ensilage of green fodder have not, as yet, 

 been determined, and we have much to learn in regard 



