1914] Lipmaii-Burgess : Ammonification in Soils by Pure Cultures 151 



B. mesentericus. Then follow, not far behind B. proteus vulgaris, 

 B. tumescens, B. ramosus, and B. vulgaris in the order named, 

 the latter being more than 331/3 per cent short of the efficiency 

 exhibited by B. mesentericus. Nearly all of the other organisms 

 fall more than 50 per cent short of the efficiency of the last- 

 named organism under this set of circumstances, namely, sandy 

 soil with tankage. There are, therefore, but five organisms out of 

 the fifteen tested which can be adjudged distinctly efficient 

 ammonifying organisms under these conditions. B. mycoides 

 again exhibits a low efficiency, and not far different from, though 

 slightly below, that manifested by it in the same soil in the dried- 

 blood series. 



It must be added here that, with the exception of B. mesen- 

 tericus, the efficient organisms in this part of Series II have also 

 shown more or less marked efficiency in the preceding series. 



The Clay-Loam Soil 



Most of the organisms tested in the clay-loam soil seem to 

 have found the latter a more congenial medium for ammonifica- 

 tion with tankage than they did when dried blood was present. 

 In this part of Series II, three of the organisms, namely, B. 

 mesentericus, B. viUgat^is, and B. tumescens, were not only the 

 most efficient ammonifiers but also about equal in their ammoni- 

 fying power. It appears, therefore, that so far as tankage is 

 concerned B. mesentericus is an equally efficient ammonifier in 

 the clay-loam and sandy soils. B. tumescens has previously 

 established its pre-eminent position among the fifteen organisms 

 as an ammonifier of dried-blood nitrogen in the adobe soil, but 

 B. vidgatus enters here for the first time as a markedly efficient 

 ammonifier. 



Only slightly behind the three organisms just discussed in 

 their ammonifying efficiency as regards tankage nitrogen in the 

 clay-loam soil are, in the order named, B. suhtilis, B. mycoides, 

 and B. vulgaris. While the latter has manifested its high 

 efficiency in other series above described, the first two organisms 

 named for the first time in the work thus far described show 

 marked ammonifying ability. Only three organisms in this part 



