3OO AGRICULTURAL BACTERIOLOGY. 



largely deprived of air. Air, of course, gets in around the 

 top, but little or none around the sides or bottom, so that only 

 the superficial layers are affected by it. This is an important 

 factor in the preparation of silage, and upon the successful ex- 

 clusion of air the character of the product is, in part, dependent. 



In the silo important and profound changes take place. The 

 first phenomenon to be noticed is the development of a large 

 amount of heat, resulting in a rapid rise in temperature. The 

 extent of this rise in temperature is dependent upon the amount 

 of oxygen present, and the readiness with which the heat is radi- 

 ated. Under some conditions a temperature as high as 1 50 F. 

 is produced, while in other cases the temperature is consider- 

 ably lower. The proper production of silage docs not appear to 

 be dependent upon this rise in temperature, inasmuch as per- 

 fectly normal silage may be made in small vessels where 

 hardly any rise in temperature is noticeable (not over 70 F.). 



This high temperature lasts a few days and then the mass 

 slowly cools. The production of heat appears to be very 

 rapid for a few days and then somewhat quickly declines, but 

 a less rapid evolution of heat continues for a long time, per- 

 haps several weeks. After the reduction in temperature other 

 changes begin which are much slower, and after several weeks 

 the character of the material is found to be greatly changed. 

 It develops a certain amount of acid, its chemical nature is 

 somewhat altered, and it develops a new flavor and aroma 

 which should be distinctly aromatic but with no signs of putre- 

 faction or mustiness. There is found to be a considerable loss 

 of material, a loss ranging from 4 per cent, to 40 per cent. 

 This is a very wide range, and shows that the method of en- 

 silage has an extraordinary effect upon the product obtained. 

 The loss is largely parallel to the amount of oxygen which 

 finds its way into the silo, being greatest when the amount of 

 oxygen is great, and very slight if the oxygen of the air be 

 thoroughly excluded. The loss is chiefly a loss of carbohy- 



