Studies of Bacillus Radicicola of Canada Field Pea 



49 



ground fine, and then introduced into test tubes 25 x 180 millimeters in size. 

 Each tube was filled to one-third its capacity. Twelve test tubes were 

 prepared for each medium, plugged with cotton, and sterilized m the 

 autoclave for one hour at 15° C. For inoculation 10 cubic centimeters 

 of sterile water in which the organisms were suspended was added to each 

 test tube. At the end of two weeks the test tubes were sealed with 

 paraffin in order to reduce evaporation. All the cultures were kept in 

 the laboratory at room temperature. 



Three tests were made in order to determine the infecting power of the 

 organism propagated on the various media. The first test was made at 

 the end of the third week, the second at the end of the tenth week, and 

 the third at the end of the twentieth week. In these tests one test tube 

 was taken from each of the media, the total number of organisms in each 

 of these tubes was determmed by the plate method, and Canada field pea 

 plants were moculated. 



The plants were gro\vn in sterilized sandy soil in flowerpots, three 

 flowerpots bemg inoculated with each culture. When the plants were 

 three weeks old they were examined and the nodules on each plant were 

 counted. In table 9 is given a description of the three- weeks-old growth 



TABLE 10. 



Number of Organisms in the Various INIedia at the Time the Tests 

 Were Made 



Medium 



Number of organisms per gram 



Cultures • 

 three weeks old 



Cultures 

 ten weeks old 



Cultures 



twenty 



weeks old 



Soy bean hay 



Soy bean roots 



Canada field pea hay 



Canada field pea roots 



Canada field pea seeds 



Compost 



Partly decomposed cow feces 



Fresh cow feces 



Corn meal 



Sawdust 



Wheat bran 



Wheat middlings 



Sandy soil 



Muck 



Cornstarch 



1,500,000 



10,000,000 



340,000 



120,000 



60,000 



7,200,000 



32,000 



10,000,000 



4,000,000 



60,000 



620,000 



200,000 





 

 Few 

 ,000 

 ,000 

 ,000 

 ,000 

 ,000 

 ,000 

 ,000 

 ,000 

 ,000 

 ,000 

 ,000 

 ,000 















306,000,000 



185,000,000 



75,000,000 



75,000,000 



440,000,000 



Contamination 



3,000,000 



370,000,000 



390,000,000 



37,000,000 



222,000,000 



55,000,000 



120,000,000 



3,240,000,000 



810,000,000 



97,000,000 



3,500,000 



600,000,000 



420,000,000 



20,000,000 

 240,000,000 



97,000,000 



