Studies of Bacillus Radicicola of Canada Field Pea 13 



Distilled water was used for watering the plants in experiments 1, 2, 3, 

 4, 5, 6, 7, 8, and 9. In experiments 10, 11, 12, and 13, boiled tap water 

 was used. 



The plants in all the experiments were grown in the greenhouse. When 

 special precautions were necessary to guard against contamination during 

 the growing period, the plants were kept in an especially constructed 

 culture room. For this purpose a part of the greenhouse was set off by 

 a partition. Cracks in the walls and around the panes of glass were 

 filled with plaster of paris. For ventilation, two panes of glass were 

 replaced by a special frame fitted with a layer of cotton held between 

 two pieces of cheesecloth. 



Inoculations 



Inoculations were made at the time of planting the seeds or within a 

 day or two following. The culture of the organism to be used for in- 

 oculation was introduced into sterile water, and the mfusion was then 

 added to the soil or the water culture in which the plants were grown. 

 In some experiments quantitative inoculation was made, in which a spe- 

 cific amount of the infusion was added. 



Exarnination of plants for nodules 

 Nodules usually appeared in about two weeks. The plants were exam- 

 ined at the end of three weeks. The roots were washed and the nodules 

 were comited, and a note was made of the size and the place of attachment 

 of the nodules. Since the soil in the vicinity of Ithaca is well inoculated 

 with the Canada field pea organism, plants kept longer than three weeks 

 were subject to some contamination. 



Special method for growing plants under sterile conditions 

 For certain experiments it was necessary to maintain absolutely sterile 

 conditions throughout the period of experiment. The method emploj'ed 

 was as follows: A large glass cylinder, 65 centimeters high and 

 10 centimeters in diameter, was used as a growth chamber. In the bottom 

 of the cylinder a few pieces of broken flowerpot were placed and were 

 just covered with water, and on the top of these was set a four-inch pot, 

 filled with a sandy soil. The cjdinder was plugged with cotton, through 

 which was passed a glass tube 7 millimeters in diameter and 65 centi- 

 meters long, the lower end resting on the surface of the soil in the pot 



