SILAGE. 231 



changes in the plant tissues, and 3. The action of enzymes. The 

 probability is that, as in the other cases where there has been a 

 similar dispute, all three processes are concerned. 



Respiratory Changes. The living plant cell is always carrying 

 on the physiological process of respiration, a process quite similar 

 to respiration in animals, and resulting in the use of oxygen and the 

 evolution of carbon dioxid. In this respiration carbohydrate 

 bodies are used, with some albuminoids as well, and heat is evolved. 

 Now, the plant cells do not die when the plant is cut down, but con- 

 tinue for some considerable time to carry on this process of respira- 

 tion. Cutting the plant to pieces appears, indeed, to increase 

 temporarily rather than to decrease the respiratory changes. 

 These may go on for several days, until, indeed, the plant cells are 

 fully dead. These are well-known facts, and recognized by botanists 

 for a long time. To these respiratory changes is due part of the 

 fermentation in silage. After the material is packed in the silo the 

 plant cells remain alive for several days and carry on these respira- 

 tory changes as long as they are alive and have oxygen at their com- 

 mand. This results in the gradual oxidation of the carbohydrate 

 material and the evolution of carbon dioxid. These changes are 

 thought to be fully sufficient to explain the first changes in the 

 silage, with the initial heating and evolution of gas. 



Fermentations Due to Enzymes. As already noticed, living plant 

 tissues secrete a variety of enzymes with varying powers of acting 

 upon carbohydrates and albuminoids. Such enzymes are present 

 in the corn stalks and fruit, and when these are packed in the silo, 

 the enzymes are of course stowed away with them. As the mass is 

 warmed up under the action of the respiratory process it is inevitable 

 that the enzymes will begin their action, and that the fermentations 

 occurring during the next few weeks will be affected by these 

 enzyme activities. It has as yet been impossible to say to what 

 extent the enzyme action is concerned in the phenomenon. Certainly 

 they must have much to do with the result. 



The respiratory processes and the action of the enzymes to- 

 gether are capable of producing silage of ordinary type without the 

 aid of bacteria or other living agencies. Silage can be made in 



