BACTERIA IN THE RIPENING OF CORN SILAGE 49 



DISCUSSION 



As stated before the investigation reported in this paper does 

 not warrant very definite conekisions and the following sugges- 

 tions are offered tentatively. It is a v^ell known fact that the 

 groups of colon-aerogenes bacilli, of streptococci and of lacto- 

 bacilli are widely distributed m nature and especiallj^ on fodder. 

 Lacto-bacilli were found by Heineman and Hefferan in cornmeal 

 and by Sherman on fresh corn leaves. The presence of these groups 

 in silage may therefore be considered as established. This con- 

 dition recalls observations on the so-called normal souring of 

 milk and the activity of streptococci and lactobacilli during 

 cheese ripening. Assuming that the colon-aerogenes group is 

 present in fresh silage a limited growth of these organisms would 

 produce an initial fermentation with acid and gas as the chief 

 products. This assumption is supported by the fact that con- 

 siderable pressure is developed during the ripening of silage and 

 by our observation that gas is formed in abundance in milk cul- 

 tures prepared from samples of silage in early stages of ripening. 

 The colon-aerogenes group is soon suppressed by the strepto- 

 cocci. Acid is the chief product of this group. Milk cultures 

 showed a progressive decrease of gas formation a fact which 

 indicates the gradual suppression of the colon-aerogenes group. 

 Streptococci are then crowded out by lactobacilli, but probably 

 never disappear entirely as they could be isolated readily from 

 silage in its last stages of fermentation. It is suggested that at 

 least two groups of lactobacilli are active. The first group is of 

 the slow-growing type, the bacilli occurring singly and showing 

 granular staining with methylene-blue. The second group of 

 lactobacilli is of the more rapid-growing order and is readily 

 isolated from later stages of fermenting silage. 

 ?;. Wyant inoculated corn silage experimentally with cultures of 

 Streptococcus lacticus and Lactobacillus bulgaricus and obtained 

 a product which according to the author's description resembled 

 normal silage. However, after a period of four to five weeks 

 lactobacilli were not isolated, while streptococci were recovered 

 without difficulty. This shows that the silage had not passed 



