1914] Lipman-Biirgess : Ammonification in Sails hy Pure Cultures 155 



The Clay -Loam Soil 



The most notable thing in this part of Series III is as above 

 intimated, the very low efficiency of all of the organisms tested. 

 Indeed only two organisms manifest any notable activity as 

 ammonifiers of nitrogen in cottonseed meal in the clay-loam soil 

 as a medium. These two in the order of their importance are 

 B. ramosus and Streptothrix, sp. To these, in view of the dis- 

 agreement of the duplicates as above shown, B. vulgaris may 

 probably be added, and perhaps also B. vulgatus. The other 

 organisms are all distinctly below the first two mentioned, and 

 the lowest efficiency thus far noted is that exhibited by Mic. 

 tetrage^ms in this soil. Considering the high efficiency of the 

 latter organism in Series I, the results just discussed are puzzling. 



The Clay-Adohe Soil 



Even a casual glance at the data obtained in the clay-adobe 

 soil as a medium indicates the distinct superiority of that medium 

 to the clay loam soil for ammonification of the nitrogen of cotton- 

 seed meal. Not only relatively but absolutely the data obtained 

 show the production of much larger amounts of ammonia in this 

 portion of the work. 



As is the ease in the sandy soil with cottonseed meal as the 

 ammonifiable material, B. tumescens shows its distinct superiority 

 to the other organisms as an ammonifier in the adobe soil. The 

 next most efficient organism is B. suhtilis, which, however, is con- 

 siderably less efficient ; and the next two organisms, about as far 

 below B. suhtilis in efficiency as the latter is below B. tumescens, 

 are B. ramosus and B. mycoides. The other organisms are all 

 low in efficiency, though in nearly all cases absolutely better than 

 the same organisms in the clay-loam soil. Thus far we find that 

 B. suhtilis shows itself markedly efficient, for the fir.st time, in 

 the clay-adobe soil with cottonseed meal. All the other organisms 

 above named have manifested marked efficiency in some parts 

 of the foregoing series. 



Looking at Series III as a whole it is interesting to note that 

 the nitrogen of cottonseed meal seems to be made available 

 through the activity of pure cultures of ammonifying bacteria, 



