10 Martin J. Prucha 



development in Canada field pea when the plant is grown in water or 

 soil cultures; (3) A study of the influence of various environmental con- 

 ditions on the infecting power of the organism. 



METHOD OF INVESTIGATION 



Organism 

 Bacillus radicicola from Canada field pea was used for all the experiments 

 except number 11, for which the organism from alfalfa was used. The 

 organism was isolated as described on page 14. The stock culture was 

 kept in the laboratory on agar slopes of medium 335, and was exposed 

 to diffused light during the entire investigation. It was transferred at 

 irregular intervals of time varying from one to three months. 



Aledia 

 The various kinds of media used are referred to in the text by their 

 laboratory numbers. In table 1 are given the laboratory numbers and 

 the composition of the principal media emploj'ed. In addition to these 

 a number of other media were used, and these are described subsequently. 

 All the media were prepared accordmg to the recommendations on the 

 Descriptive Chart of the Society of American Bacteriologists. 



Sterilization of utensils 



Strict precautions were observed in sterilizing all the utensils. Glassware 

 was sterilized for two hours at from 150° to 170° C. Scalpels and similar 

 instruments, which resist high temperature, were heated m the flame. 

 For work requiring air free from dust, a room was used into which a 

 stream of steam was allowed to flow until the air was saturated; after 

 condensation of the steam, the air in the room was conspicuously free 

 from any dust. 



Sterilization of seed 



The experiments in Part III required seed free from B. radicicola. It 

 was necessary, therefore, to sterilize the seed. In experiments 10 and 11, 

 95-per-cent alcohol was used, the seed being treated for thirty seconds. 

 In experiments 12 and 13 a solution of bleaching powder was used. The 

 author is indebted for this method to Professor J. K. Wilson, of Cornell 

 University. The solution is prepared by mixing 8 grams of bleaching 



