388 EXPERIMENTS WITH PLANTS 



air-tight compartment with Corn (or some other plant) 

 chopped into small pieces. It is packed into a solid 

 mass; frequently pressure is used to solidify it. The 

 top is covered (so as to prevent the access of air). A 

 rapid rise in temperature occurs (sometimes going as 

 high as 150 F.) ; after a few days the mass cools, but 

 the evolution of heat continues to a lesser degree for 

 several weeks. At the end of this time it is found to 

 be somewhat acid, with a fine aromatic flavor which 

 causes it to be eagerly eaten by cattle. Silage can be 

 made just as well in small pails or tubs as in larger 

 quantities, and the phenomena here described can be 

 observed (only the rise in temperature will be very 

 small) in the school -room. 



The whole process looks like fermentation, and was 

 until recently supposed to be due to bacteria; the 

 latest studies indicate that bacteria have little or noth- 

 ing to do with it, especially in the early stages, where 

 the rise in temperature seems to be due to the activity 

 of the wounded plant- cells. In this respect there is a 

 close agreement between animal- and vegetable -cells 

 in the rise of temperature (or fever) which follows a 

 wound. 



The fermentation of tobacco, long supposed to be 

 due to bacteria, has lately been referred to the self- 

 activities of the cell's of the leaf: this subject is still 

 somewhat in dispute. 



The "sweating" of hay is in all probability a similar 



