EXPERIMENT STATION REPORT. 289 



(82°), but there was a fall of 5° in the course of the next 

 two days. A rise of temperature then followed, reaching 

 the maximum of 87° on the 16th, and during the next two 

 weeks there was a depression of but 9°. The fall in tem- 

 perature in the following two and one half months was only 

 29° to the lowest observation recorded (49°), which is still 

 above the temperature of the outside air. 



Bacteria. 



Samples of the ensilage were taken from time to time 

 through the tube, at depths of from four to five feet below 

 the surface, for microscopic examination. 



The sample taken on the 9th inst., when the temperature 

 was observed, swarmed with bacteria, which were remarka- 

 bly active, and rapidly increasing by self-division. 



Since the temperature has fallen below G0° the apparent 

 activity of the bacteria has been slightly diminished. This 

 may be attriluited to the lower temperature and increasing 

 acidity, but the relative influence of each has not been de- 

 termined. 



Fermentation.'' 



There are two classes of ferments now generally recog- 

 nized : 1st, the so-called soluble or chemical ferments, as 

 acids and diastase, which " invert" cane sugar and transform 

 it into dextrose, or change starch into dextrine, etc., and 

 these, according to Dumas, "always sacrifice themselves in 

 the exercise of their activities." 2d, The true ferments, 

 which from the discoveries of Schwann (1838), and the 

 elaborate and exhaustive experiments which have been 

 made by Pasteur in the past twenty years, are now known 

 to be living organisms that produce fermentation as a func- 

 tion of their vital activity. 



The true fermentations are, therefore, purely physiological 

 processes, which are defined by Pasteur as " the direct con- 

 sequence of the processes of nutrition, assimilation and life, 

 when they are carried on without the agency of free oxygen," 

 or " as a result of life without air." Unlike the soluble fer- 

 ments, these living organisms increase at the expense of the 

 substances fermented. 



