BACTERIA IN THE RIPENING OF CORN SILAGE 51 



of some investigators that the first process of silage ripening is a 

 respiratory process (Babcock and Russell) is not excluded by 

 the hypothesis advanced and does not interfere with it. Fur- 

 thermore, mention should be made of the fact that at no time 

 was growth of yeasts m the silage observed, although yeast 

 cells were invariably present. Growth of yeast was observed 

 only when an extract of silage was incubated at 37°C. There is 

 therefore in this investigation no indication of an alcoholic or 

 acetic acid fermentation as suggested by Esten and JVIason. 



It should be emphasized that the assumption of different 

 phases of silage fermentation does not mean that the phases are 

 distinctly separated, or that a period of rest occurs when one 

 phase passes into the next one, or finally that the same phase is 

 operative throughout the whole quantity of silage. The authors 

 are inclined to the opinion that conditions of ripening are not the 

 same in different parts of the silage and that unless samples are 

 taken from definite regions, if this were possible, the progress of 

 ripening would appear somewhat obscured. It is suggested 

 further that the process of ripening may dift^r in kind and in 

 degree in different silos, owing to variations in construction, in 

 moisture content, and to climatic conditions. However, the 

 fundamental principles and the groups of organisms active in 

 the fermentation of silage are sunilar under a variety of conditions. 



REFERENCES 



Babcock, S. M., and Russell, H. L. 1900 Causes operative in the production 



of silage. Ann. Rep. Wis. Agri. Exp. Sta., 123-141. 

 Esten, W. M., and Mason, C. J. 1912 Silage fermentation. Conn. Agri. Exp. 



Sta., Bull. 70. 

 GoRiNi, Constantine 1919 Studi sui silo lattici in base alia fisiologia micro- 



bica. Reale istituto Lombardo di scienzae letters, 52, 192-205. 

 Heineman, p. G., and Hefferan, M. 1909 A study of B. bulgaricus. Jour. 



Inf. Dis., 6, 304-318. 

 Hunter, O. W., and Bushnell, L. D. 1916 The importance of Bacterium bul- 



garicum group in ensilage. Science, N.S., 43, 318-320. 

 Sherman, James M. 1916 A contribution to the bacteriology of silage. Jour. 



Bact., 1, 445. 

 Wyant, Zae Northrup 1920 Experiments in silage inoculation. Abstr. 



Bact., 4, 6. 



