14S rniversity of California Puhlicalions in AgricnlturaJ Sciences [Vol. 1 



eliminates the fear that physical conditions in the individual 

 cultures might operate to produce the rather marked effects noted. 

 In a comparison of the three soils it appears that the follow- 

 ing organisms are among those which show the highest efficiency 

 in transforming the nitrogen of dried blood into ammonia : Ps. 

 putida, Sarciua lutea, B. vulgaris, B. proteus vulgaris, Mic. 

 tetragenus, B. tumescens. Of these organisms only Mic. tefra- 

 genus shows a high efficiency in all three soils. Of the others 

 B. vulgaris shows a high efficiency in both the sandy and adobe 

 soils and Ps. putida, in the sandy and clay-loam soil. The rest 

 namely Sarcina lutea, B. proteus vulgaris and B. tumescens, are 

 markedly efficient only in one soil each, namely, the sandy soil for 

 the first, the clay-loam soil for the second, and the clay-adobe 

 soil for the third. It appears to us particularly worthy of note, 

 also, that of the last three organisms named B. proteus vulgaris 

 and B. tumescens each holds a pre-eminent position of efficiency 

 in its own soil which no other organism of the fifteen has 

 approached; and even in the case of Sarcina lutea we find that 

 it occupies a position in efficiency in its favorite soil which is 

 second only to that of B. vulgaris and not very far behind the 

 latter. This rather remarkable condition would hardly seem to 

 be accidental and appears to us to indicate for certain organi-sms 

 marked preferences for certain physical characteristics in media 

 in which they are grown. 



It must be added here. too. that only six of the fifteen 

 organisms show marked ammonifying efficiency as regards the 

 nitrogen of dried blood even Avhen tested in three widely different 

 soil types. The others vary but little from one another in all 

 soils. Oddly enough, the organism which has shown the highest 

 ammonifying efficiency because it maintained it through all soils, 

 namely, Mic. tetragenus, has never before been looked upon, so 

 far as we are aware, a.s an important ammonifier. That it should 

 be the only one of fifteen organisms tested which should be about 

 equally efficient in all soils used is not unworthy of note. 



It is further significant to note here that B. mijcoidcs, which 

 has always been regarded as one of the most efficient soil organ- 

 isms at ammonification, does not in our experiments show any 

 unusual activitv in that direction, at anv rate when dried blood 



