BACTERIA IN THE RIPENING OF CORN SILAGE 47 



times the original amount, but after forty-eight hours a marked 

 decrease of acidity was observed coincident with the development 

 of a heavy film consisting of yeast cells; 



A bacillus of the colon-aerogenes group was present in large 

 numbers, but only in smears prepared from silage during early 

 stages of fermentation. During late stages the bacillus may 

 still have been present, but if so was numerically insignificant. 

 Streptococci and lactobacilli were always present in early as 

 well as in late samples. The streptococci were readily isolated 

 by plating, but the lactobacilli did not grow readily on ordinary 

 media and were isolated by the method employed by Heineman 

 and Hefferan, namely by repeated transfers through milk and 

 final plating on whey agar. 



The streptococci isolated varied somewhat morphologically. 

 In some cases the diplococcus form was predominant, while in 

 others chain formation was observed. However, the diplococcus 

 form was found chiefly in early samples of silage, while chain 

 formation was abundant in later samples. Chains were prom- 

 inent also in stock cultures prepared from the isolated strepto- 

 cocci, but the short form reappeared when fresh subcultures 

 were prepared. The fact has been repeatedly recorded, that 

 during the most a,ctive period of growth, streptococci, especiallj^ 

 saprophytic ones, appear chiefly in diplococcus form, while 

 after the maximum growth has passed chain fonnation becomes 

 more evident. The size of individual cells of streptococci con- 

 firms the assumption that they are more active in early silage 

 than in the ripened product. From early samples the cells 

 were uniformly small and in later samples they were large and 

 frequently appeared swollen. These abnormal forms disap- 

 peared when young generations grew on inoculated media. 



The amount of acid formed in glucose broth by the strepto- 

 cocci was determined by titration with n/20 NaOH. The 

 quantity thus determined never exceeded 5 per cent normal 

 acid in five days. Milk was readily coagulated by most strains 

 of streptococci isolated, in some cases within twenty-fotir hours. 



The lactobacilli observed occurred singly, showed granular 

 staining with methylene-blue in manj^ instances and were rather 

 difficult to isolate. They grew slowly on media containing 2 



