Mar. =4, 1919 Ammonification of Manure in Soil 333 



II.— TAXONOMIC STUDY OF TWO IMPORTANT SOIL 



AMMONIFIERS 



By H. J. Conn 

 DISTRIBUTION 



The preceding section of this paper is concerned with the ammonify- 

 ing powers of two soil bacteria, P seudomonas fiuorescens (Fliigge) Migula 

 and Ps. caudatus (Wright) Conn. Both of them are beUeved to be very 

 widely distributed in nature. There is no question as to the wide distri- 

 bution of Ps. fliwrescens, because it has been described again and again 

 by previous investigators as occurring in various localities. This, or 

 some other similar organism, has been found most frequently in soil and 

 in water; but has also been reported in air, butter, maple sap, and other 

 substances. It has been obser\'ed by the present writer in practically all 

 soils investigated, especially in soil that has been aerated or manured. 

 Ps. caudatus is probably equally widely distributed; but the difficulty in 

 recognizing it from published descriptions renders the literature concern- 

 ing it of doubtful value. No references to similar organisms in soil have 

 been found, but various writers have described yellow or orange liquefy- 

 ing bacteria found in water, some of which are undoubtedly the same as 

 the organism studied here. Water was the source of Wright's Bacillus 

 caudatus. The writer has observed it in water and in many soils, 

 especially in freshly manured soil. 



To aid in the identification by others of these two organisms studied by 

 Bright, a detailed investigation of their physiology and cultural charac- 

 teristic's has been made, and the characteristics obser\^ed have been 

 compared with those described by other writers. The following paper 

 contains a description of these characteristics and a discussion of the 

 probable relationships of these organisms in others. 



PSEUDOMONAS FLUORESCENS 



Pseudomonas fiuorescens (Fliigge) Migula {1900, p. 886) was first de- 

 scribed by Fliigge {16, p. 289) as "Bacillus fiuorescens liquefactens." The 

 description is rather meager, but the organism is plainly specified as a 

 motile short rod, liquefying gelatin rapidly with the formation of a 

 greenish-yellow fluorescence, producing a brownish growth on potato, 

 and occurring in water and in decomposing material. This description 

 indicates beyond question the group of fluorescent pseudomonads, even if 

 the exact species or variety is uncertain. In the later edition of this book 

 (Kruse, 26, p. 292) the organism is described more definitely with the 

 following additional information: Size 0.3 to 0.5 by i to 2 m; no spores; 

 Gram stiin negative ; optimum temperature 20° to 25° C. Kruse further 



