46 p. G. HEINEMAN AND CHARLES R. HIXSON 



The silage iii the three silos was removed from the top as it 

 was required as food for cattle. Therefore the samples obtained 

 for investigation had not only fermented during progressively 

 longer periods of tune, but since the surface layers were period- 

 ically removed samples had to be procured from increasing 

 depths. It is conceivable, therefore that anaerobic fermentation 

 becomes more pronounced as silage ripens. 



METHODS 



Samples were taken from the silos in November, January, 

 February, March, April, May and June. A few days elapsed 

 between sampling the different silos in order not to crowd the 

 work but this short interval probably made no material dif- 

 ference in the relative stage of fermentation. Ten grams of each 

 sample were infused with 50 cc. of cold physiologic salt solution. 

 From this infusion stains were prepared and inoculations made in 

 milk with addition of brom-cresol-purple as indicator, into 

 flasks and fermentation tubes containing 2 per cent glucose 

 broth, and on agar. The last medium was used for surface and 

 stab cultures. The infusion of silage was titrated with n/20 

 NaOH with phenolphthalein as indicator and then together 

 with the inoculated media was incubated at 37°C. 



RESULTS 



Stains from the silage infusion showed enormous numbers of 

 microorganisms. No attempt was made to enumerate them or 

 separate the types, but the predominating types were noted 

 and cultivated. Yeast cells were invariably present and fre- 

 quently formed a solid film on the surface of the incubated 

 infusion. The acidity of this infusion was never more than 3 

 per cent normal, but ti is probable that the salt solution did not 

 dissolve all the acid contained in the silage. If the juice had 

 been pressed from the silage and then diluted five times its 

 volume with salt solution the acidity would probably have 

 proved higher than the values obtained. After 24 hours incu- 

 bation of the silage infusion the acidity rose to about three 



