102 University of California Publications in Agricultural Sciences [Vol. 1 



of Series II have shown themselves to be really weak ammonifiers, 

 and they are B. proteus vulgaris, B. icteroides, and Mic. tetra- 

 gonis. The first and the third of these, it will be remembered, 

 have given evidence of marked efficiency under other circum- 

 stances, but the second has thus far been throughout an organism 

 of low efficiency. It is striking to note the much greater uni- 

 formity which exists in this portion of Series II in the ammoni- 

 fying powers of four-fifths of the organisms tested than that 

 which obtains in other parts of this series and of other series. 



The Clajj-Adohc Soil 



Plere again we find the great uniformity in ammonifying 

 power between the larger number of bacteria tested which is 

 characteristic of the foregoing section of Series II. On the other 

 hand, the clay-loam soil seems to have been a more congenial 

 mediiim than the adobe soil for the ammonification of tankage 

 nitrogen, for larger amounts of ammonia are produced in it by 

 the same organisms in the same period of incubation. 



Sarcina lutea shows the highest efficiency as an ammonifier 

 in this part of the series, but is only slightly more efficient than 

 B. tiimescens. The organism taking third place is B. mycoides 

 which, indeed, is not far liehind the other two. Next in order of 

 importance and still very efficient ammonifiers are B. suhtilis and 

 Streptothrix, sp. The other organisms are considerably weaker 

 ammonifiers than those just mentioned and B. icicroides again 

 proves to be distinctly the weakest. Both Sanina luica and 

 B. tuniescens have, as mentioned above under other circum- 

 stances, plainly evidenced their high efficiency as ammonifiers 

 and B. mycoides and B. suhtilis have taken similar positions with 

 respect to tankage in the clay-loam soil. Streptothrix, sp., it will 

 be remembered, has also shown a high ammonifying power before 

 in the case of the clay-loam soil when dried blood was used. 



Comparing the three soils in this series with the same ones 

 in the preceding series, it appears quite clear that taking them 

 by and large, annnonifying bacteria manifest a much higher 

 efficiency with high-grade tankage than with dried blood under 

 similar conditions. Likewise also, in Series II a small number of 



