EXPERIMENT STATION BULLETINS. 



477 



a coutinued ammonia formation. The increase in cells would have to be 

 very large, for the three to five fold number of lactic bacteria caused 

 only a doubling of the acid, and here we are dealing with an increase 

 of 6 to 8 times the original amount of ammonia. 



For the experiments with counting bacteria, B. mycoides was 

 not considered a suitable organism, because such thread bacteria do 

 not alloAV of great accuracy in plating. Three pure cultures of bacteria 

 were isolated for this purpose from putrefying peptone solution. They 

 were ammonia producers and formed an even cloudiness without scum 

 in liquid media; the species names were not determined. The tcchnic 

 of their culture varied from that of the first exj>eriment. The actual 

 medium was a 1% solution and this medium was used as such, and 

 mixed with sand in two proportions: 100 g. of sand (medium 

 quartz) + 50 cc. solution and 200 g. of sand + 20 cc. of solution. 

 Thus, there were three conditions established, the solution, the water- 

 logged soil (the liquid stood a few millimeters over the sand) and the 

 well-aerated soil. The bacteria were counted on agar plates, each number 

 representing the aA^erage of two counts from the same sample. The ex- 

 periments were carried out by Mr. A. Itano and Mr. Eugene Brown. The 

 ammonia is computed per 100 cc. of solution, the bacteria per cc. 



The results are, on the whole, not satisfactory. The counts in Exp. 

 X were so unsatisfactory that they are entirely omitted. All three 

 sets of data show the same general occurrence: increased number of 

 cells as well as increased ammonia formation in the well aerated sand 

 cultures. The increase in the numbers is not high enough, however, 

 to account for the ammonia increase. 



TABLE X. 

 Milligrams Ammonia in 100 cc. of Peptone solution. 



TABLE XL 



