] m 4 I Lipman-Burgess : Ammonification in Sails by Pure Cultures 149 



is used as the ammonifiable material, no matter what the soil 

 medium. A possible exception to this statement may be found 

 in the case of the adobe soil, in which B. mycoides seems to be 

 superior to all but three or four of the fifteen organisms tested. 

 Such superiority, under the circumstances noted, is probably of 

 little significance. 



Series II. Experiments with Tankage 



This series was arranged in a manner similar to the preced- 

 ing, the sandy, clay loam, and clay-adobe soils again being used 

 as media, but the ammonifiable material in this case was a high- 

 grade tankage, the nitrogen content of which was 9.62 per cent. 

 The results of the ammonia determinations were as shown in 

 Table IV on page 150. 



Discussion of Series II 



The Sandy Soil 



When we study in the foregoing table, the ammonification of 

 tankage by pure cultures of bacteria, and compare the results 

 with those of Table III, we see at once some very striking differ- 

 ences between the ability of the same micro-organisms to produce 

 ammonia from tankage and from dried blood respectively. Not 

 only do more of the organisms show a high efficiency in trans- 

 forming the tankage nitrogen to ammonia, but the point of 

 highest efficiency is not reached by the same organisms as before, 

 others having taken their places in this series with sandy soil as 

 the culture medium. For example, we find that B. mesentericus, 

 which iu the preceding series showed throughout an extremely 

 low ammonifying efficiency even in the sandy soil, now manifests 

 in the same culture medium, which, however, has tankage in 

 place of blood added to it, the highest efficiency of all of the 

 organisms tested. Indeed, it occupies a position of its own in 

 that direction, much as does B. vidgaris in the sandy soil of the 

 last series. The organism which approaches it most closely in 

 the same medium is B. proteus vidgaris which, however, falls 25 

 per cent short of producing the amount of ammonia yielded by 



