Studies of Bacillus Radicicola of Canada Field Pea 47 



was added, the amount of growth was decidedly reduced on media 334 

 and 335 and the infecting power also was reduced. The influence of this 

 amount of acid in medium 337 was not so pronounced. The addition 

 of 1 cubic centimeter or more of the acid solution completely inhibited 

 the growth and the infecting power of the organism on all three 

 media. 



The addition of 0.1, 0.5, 1, 1.5, and 2 cubic centimeters, respectively, of 

 the normal solution of NaOH, to 10 cubic centimeters of each of the media, 

 increased the amount of growth and also the effectiveness of the inoculation. 

 The addition of 3 cubic centimeters of the normal solution of NaOH 

 reduced the amount of growth and the infecting power. The heaviest 

 growth took place on medium 337 to which the above amounts of NaOH 

 were added, but the plants inoculated with these cultures did not produce 

 as many nodules as did the plants inoculated with the organisms propa- 

 gated on media 334 and 335 — a fact that suggests the possibility of 

 a reduction in infecting power. 



The addition of cane sugar to medium 334 in the amounts indicated 

 in table 8 has a beneficial influence on the multiplication of the organism. 

 The infecting power does not seem to be affected by it. All the cultures 

 in which any multiplication was observed produced positive inoculation, 

 so that the infecting power of the organism was not destroyed. The 

 variations in the number of nodules on the plants inoculated by the 

 different cultures seem to indicate that the organisms propagated on 

 medium 337 partly lost their infecting power. This measure of infecting 

 power, however, is not accurate, and other explanations might easily 

 be supplied. The most noticeable point was that positive inoculation 

 was produced by all the cultures in which any multiplication took place, 

 so that the growth and the infecting power seem to run parallel. 



EXPERIMENT 12 

 INFLUENCE OF SOME OTHER MEDIA 



The organism, isolated as described in Part I, was kept in the laboratory 

 for two years on agar slopes, medium 335, before this experiment was 

 started. During this time the organism was continually exposed to 

 diffused light and to the ordinary variations in temperature and humidity. 

 The organism was then propagated on agar slopes, medium 334, to which 

 various substances were added as is indicated in tables 9 and 10. Twelve 



