Studies of Bacillus Radicicola of Canada Field Pea 19 



mentation tubes. From dextrose, maltose, and saccharose it produces a 

 slight amount of some acid. Neutral litmus milk becomes alkaline after 

 the organism has grown in it for about two weeks. 



The organism of Canada field pea does not have any strikingly charac- 

 teristic colony features by which it can be distinguished from other 

 microorganisms. The group number of the organism, according to the 

 chart of the Society of American Bacteriologists, was found to be 

 B. 222.2322033. 



PART II. INFLUENCE OF CERTAIN FACTORS ON NODULE PRODUCTION 



The literature on the general subject of legume inoculation is very 

 extensive; yet knowledge concerning the factors that influence nodule, 

 production is suprisingly meager. For the most part the investigations 

 on this point are incidental and fragmentary. It has been shown by 

 various investigators, however, that the nature of the medium in which 

 the plant is grown has an influence on the production of nodules. 



Rautenberg and Klihn (1864) grew Vicia faba in various nutrient 

 solutions, and incidentally observed that in the nitrogen -free solution the 

 beans developed an abundance of nodules, while in the solutions con- 

 taining nitrogen no nodules were produced. 



Hugo de Vries (1877) made a similar observation. He grew red clover 

 in nutrient solutions, and the plants developed a large number of nodules 

 ia the nitrate-free solution but only a few or no nodules in the solution 

 containing nitrates. 



Vines (1888-1889) tested the influence of potassium nitrate on nodule 

 development on Vicia faba grown in nutrient solutions and also in the 

 soil. His experiments showed that potassium nitrate tends to inhibit 

 nodule development, both in soil and water cultures. 



Frank (1889) grew lupines and peas in humus soil and in humus-free, 

 soil. He found that the plants grown in the humus-free soil developed 

 an abundance of nodules, and those grown in the soil rich in humus had 

 no nodules. He offered the following explanation for this: " The lupines, 

 and also the peas, obtain the same benefit from the nodule fungus as they 

 do from the humus. Where humus is present, the plants prefer to obtain 

 the nourishment from the humus and no nodules are developed; where 

 humus is wanting, however, the nodule fungus infects the plants."* 



^ Translation from the original German. 



