1914] Lipman-Burgess : Ammonification in Soils by Pure Cultures 159 



one another, B. vulgatus, Ps. putida, B. ramosus, and B. tiinies- 

 cens. All of these, however, fall more than 30 per cent short of 

 attaining the ammonifying efficiency of B. megatherium under 

 the conditions here considered. Two other organisms, B. subtilis 

 and Sarcina lutea, fall 40 per cent short of the efficiency of B. 

 megatherium, and the others all fall far below even that figure. 

 It is singular, here again, that the physical nature of the soil 

 medium employed should so strikingly and so variously influence 

 the efficiency of the ammonifying bacteria. The two organisms 

 which are distinctly superior in ammonifying ability as regards 

 the nitrogen of fish guano in the clay loam soil were only of 

 moderate efficiency with the same form of nitrogen in the sandy 

 soil. And again, the organism which in the latter soil was 

 paramount in its position retreats in the clay-loam soil to third 

 place. 



The Clay-Adohe Soil 



This is the first series of those we have thus far considered, 

 as the data in Table VI shows, in which the clay-adobe soil proves, 

 on the whole, to be inferior to the clay-loam soil. Seven organ- 

 isms out of fourteen here show an extremely low ammonifying 

 efficiency, and two others are by no means efficient organisms. 

 That leaves five organisms in this group which may be considered 

 of importance. Of these, B. vulgaris is the most efficient, but 

 B. tumescens is not far behind it. B. suhtilis belongs to the 

 second class in this group and B. proteus vulgaris and B. 

 mijcoides to the third class. It is rather unfortunate that it was 

 not possible in this part of Series IV to obtain better agreement 

 between duplicate determinations. It would not appear to us, 

 however, that the discrepancies in question militate against the 

 justice of the conclusions above drawn. 



B. megatherium holds a very good place in the sandy and 

 clay loam soils of Series IV and a fair place in the adobe soil. 

 The same is even more strikingly true of B. vulgaris, and in a 

 minor degree this is also true of B. tumescens. The other organ- 

 isms do not manifest such consistent efficiency under the three 

 widely varying soil conditions. 



