76 Journal of Agricultural Research Voi. x,no. a 



Esten and Mason (6) conclude that microorganisms are the predominat- 

 ing factor in silage ripening, but that heat formation is the result of the 

 activity of plant cells. On the other hand, Burrill (4) states that the 

 high temperature attained in his investigations was caused by two or 

 more species of rodlike bacteria to which butyric-acid production could 

 be attributed. Lafar (11, p. 199-203) and Conn (5, p. 112-114) discuss 

 heat production in silage as the result of bacterial action. Griffiths (8) 

 describes several groups of bacteria, important in silage fermentation, 

 but makes no statement regarding silage heating. In a recent article 

 Hunter and Bushnell (9) show that microorganisms are the essential 

 cause of silage ripening. Sherman (14) suggests the probable importance 

 of acid-producing bacilli in the curing of com silage. 



Evidence is sufficient to warrant the assumption that microorganisms 

 are the influential factor in forage fermentation. It is logical to assume, 

 therefore, that the heating of ripening forage is a result of their activities. 

 With this hypothesis in mind the following investigations were planned. 



METHOD OF PROCEDURE 



Alfalfa, com, cane, and kafir forage, siloed under laboratory condi- 

 tions, were used for silage production. The forage was finely cut and 

 packed tightly in i -quart thermos fruit jars and hermetically sealed. 

 Thermos jars were used in order to prevent as much heat radiation as 

 possible. Care was taken each time to entirely fill the jars before sealing, 

 as such air spaces would afford opportunity for the growth of molds. 

 The heat thus liberated by their activities would offer a source of error 

 in the interpretation of results. In order to bring heat radiation to a 

 minimum, the thermos bottles were kept at a fairly uniform temperature. 

 In a majority of the experiments this temperature ranged between 35° 

 to 2>7° C. In a few cases, however, they were kept near 20°. Tne gen- 

 eral course of action was the same in each case. 



The temperature readings v/ere determined by the use of thermome- 

 ters and thermo-resistance coils. A type of thermometer was used 

 which allowed the extended mercury end of the thermometer to be 

 inserted to the center of the jar, while the graduations remained above 

 the neck of the bottle. It was graduated to o. i ° C. 



The resistance coil consisted of 40 feet of black- enameled magnet 

 wire. No. 36, wound around a small-sized spool. A thin coat of paraffin 

 covered the coil in order to insure perfect insulation. The wire leads 

 connecting the coil and resistance box were incased in small glass tubing 

 from the coil to the outside of the thermos jar. This was to avoid break- 

 ing the threadlike wires, especially during the filling of the jars. Each 

 was standardized with a thermometer and the resistance readings con- 

 verted into degrees. The coils also registered to o.i'^ C. All thermome- 

 ters and resistance coils were standardized against each other, and the 

 necessarv temperature corrections noted. 



