448 JAMES M. SHERMAN 



silage but that they occur in large numbers is shown by the 

 fact that sterile milk usually develops a high acidity when 

 inoculated with dilutions of silage representing only 1/1,000,000 

 of a gram of the moist material, or when inoculated with 1/1,000,- 

 000 of a cubic centimeter of the juice expressed therefrom. The 

 occurrence of the high-acid organisms in such large numbers 

 has been observed in silage over nine months old. 



The aciduric bacilli may also be readily isolated by the direct 

 plating of the silage on lactose agar on which this type can be 

 grown. In fact these organisms constitute a majority of the 

 bacteria found in ensilage during the latter part of the curing 

 process. Unfortunately, it was not possible to make a study 

 of the silage during the first two months when the most impor- 

 tant bacterial processes undoubtedly take place. Plate counts 

 made on lactose agar of the juice expressed from silage between 

 three and six months of age have given counts ranging from a 

 few thousand to over 1,000,000 bacteria per cubic centimeter. 

 As is well known, most types of the aciduric bacilli do not grow 

 well on agar plates, and it would seem very probable that the 

 actual number of such organisms is considerably greater than 

 is indicated by the plate count. That this supposition is cor- 

 rect is shown by the observation that these organisms may be 

 present in numbers approximating 1,000,000 per cubic center- 

 meter of juice,as revealed by the dilution method, when the 

 plate Count shows only 15,000. 



Counts made on silage juice by the direct microscopic method 

 of enumeration have shown the presence of from 1,500,000,000 

 to 4,800,000,000 bacterial cells per cubic centimeter, most of 

 which were slender rods. Many of the organisms observed 

 under the microscope were, in all probability, dead, since autoly- 

 sis would undoubtedly be greatly retarded in such an acid me- 

 dium. However, these observations indicate that immense 

 bacterial activity had taken place. 



The morphological and cultural characteristics of the acid 

 producing bacilli which have been isolated agree with those 

 reported by Hunter and Bushnell (1916). The rods were of 

 variable size, but the growth characters of the cultures thus 



