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SCIENCE 



[N. S. Vol. XLI. No. 1050 



pared from all of these organisms and micro- 

 scopic examinations after several transfers 

 and platings showed the forty-four cultures 

 to be pure. The form of the organisms as 

 viewed under the high power of the micro- 

 scope varied from short to long rods to oval 

 forms. The detailed results of these examina- 

 tions, however, can not be given in this brief 

 paper. 



The next step in the investigation was to 

 test the powers of inoculation of the forty- 

 four organisms obtained as above described. 

 Our procedure was as follows : A large quan- 

 tity of fertile sandy soil from Anaheim, Cal., 

 was sterilized in the autoclave for four hours 

 at about IJ atmospheres of pressure. When it 

 had cooled it was distributed in quantities 

 making a thickness of three inches in quart- 

 size glass fruit jars. The latter were then 

 securely stoppered with cotton and sterilized 

 in the autoclave, thus giving the soil a double 

 sterilization. The jars were then put away for 

 three days to allow the soil to become normally 

 aerated again, and several samples were care- 

 fully withdrawn for testing as to sterility. 

 No colonies developed on the agar plates even 

 after many days. The soil thus being shown 

 to be sterile, we proceeded with the Yicia seeds 

 as follows. The seeds were placed in a 1 to 

 1,000 HgCL solution and kept there for ten 

 minutes. They were then thoroughly rinsed 

 with distilled water and treated with concen- 

 trated H,SOj for 20 minutes to aid germina- 

 tion. They were then again thoroughly rinsed 

 in sterile distilled water and removed to a 

 sterilized moist chamber containing several 

 layers of water-saturated filter paper. The 

 seeds which thus gave perfect germination in 

 3 or 4 days as against very poor germination 

 for similar seed untreated with H.SO, were 

 then transferred to the jars with sterile forceps 

 and pressed into the soil by means of a steril- 

 ized glass rod without removing the stoppers 

 from the jars. It may be added here that every 

 jar received fifty c.c. of a .5 per cent, dextrose 

 solution to furnish optimum moisture condi- 

 tions and a proper source of energy for B. 

 radicicola. Five seeds were planted in every 

 jar and the inoculation was accomplished by 



the addition, in every case, of a 5 c.c. suspen- 

 sion of the agar slant culture with sterile dis- 

 tilled water. The jars were removed to the 

 greenhouse and remained there for fifty-four 

 days, sterile distilled water being carefully 

 added when necessary. All the plants in all 

 the jars appeared to grow equally well and 

 attained a height of about eight inches. Evi- 

 dently there was an ample supply of nitrogen 

 in the ammonia or closely related forms to 

 supply even the plants in the five control jars 

 which received no inoculation. Besides the 

 control jars and the forty-four others above 

 described, there were five jars inoculated with 

 commercial cultures as follows: (1) Farmo- 

 germ, (2) Nitrogen-gathering Bacteria, (3) 

 Ferguson's Nitrogen Fixing Bacteria, (4) 

 Mulford's Nitro-Germ (weak culture), (5) 

 Mulford's Nitro-Germ (strong culture). After 

 the period mentioned the plants were carefully 

 removed from the soil in every jar and the 

 roots examined, with the following results. 



1. No nodules were found on the roots of 

 any of the plants in the control jars. 



2. Twenty-one of the forty-four inoculations 

 with bacteria isolated from the soil above de- 

 scribed gave positive results and nodules were 

 found on the roots of some or all of the plants 

 in those jars. 



3. The balance or twenty-three inoculations 

 gave negative results and none of the plants 

 in those jars showed the presence of nodules 

 on the roots. 



4. All the commercial culture inoculations 

 produced nodules except the weak culture ob- 

 tained from one of the Mulford transfers. 



These results would seem therefore to record 

 the first isolation, so far as we know, of B. 

 radicicola directly from, the soil; to show that 

 that organism so obtained at least in some 

 forms and places can be readily made to grow 

 on agar plates in large numbers; and to make 

 desirable the use of soil extract-maltose agar 

 for such purposes. 



The writers will welcome criticisms of their 

 work which may occur to their colleagues, and 

 to be corrected if, in error, as to priority (ex- 

 cepting Gage's investigation) so far as the 

 recorded isolation of B. radicicola is con- 



