Studies of Bacillus Radicicola of Canada Field Pea 51 



slope medium 334. Some of the substances that were added to this 

 medium retarded or completely inhibited the growth; others had no 

 appreciable effect on the growth; and still others caused a decided increase 

 in the growth as compared with that on medium 334 alone. (Table 9.) 

 No visible growth was produced when the following substances were 

 added: levulose 2 per cent, phloroglucin 0.2 per cent, potassium oxalate 

 0.5 per cent, potassium citrate 0.5 per cent, Witte's peptone 5 per cent, 

 Merck's peptone 3 per cent. The growth in the remaining cultures 

 was watery, almost transparent, very viscous, especially in the presence 

 of sugars. 



The number of organisms on the agar slopes was determined when the 

 cultures were ten and twenty weeks old, and in the case of the substances 

 in which the organism was propagated the determination was made at 

 three, ten, and twenty weeks. ^ The data in table 10 show a wide variation; 

 but in general, wherever a visible amount of growth appeared on the agar 

 slopes large numbers of organisms were found. At the end of ten weeks 

 no organisms were found in the presence of salicin 1 per cent, resorcin 

 0.5 per cent, Witte's peptone 5 per cent, Merck's peptone 3 per cent, 

 potassium oxalate 0.5 per cent, and potassium citrate 0.5 per cent. At 

 the end of twenty weeks, in addition to the above no organisms were 

 found in the presence of care sugar 40 per cent, levulose 2 per cent, amyg- 

 dalin 0.5 per cent, and phloroglucm 0.2 per cent. 



Very large numl^ers of the organism were found on most of the sub- 

 stances that were ground and used as media. Wheat bran and ground 

 Canada field pea seeds each had 10,000,000,000 organisms per gram at 

 the end of three weeks. The organisms remained in a vigorous condition 

 on these media for twenty weeks, as judged by the development of colonies 

 and by the results of inoculation of the plants. In soy bean hay and 

 soy bean roots no multiplication took place, and the organisms introduced 

 at the time of seeding these two media were found to be dead at the end 

 of three weeks. 



First test of infecting power (table 11) 



Three flowerpots were inoculated with each culture, these cultures 

 being three weeks old when used. The inoculated plants were kept in 

 the greenhouse and were examined for nodule development three weeks 

 after inoculation. The data are presented in table 11 : 



