The Bacterial Diseases of the Bean 19 



Beef-infusion agar slants (pH 7.0). Growth does not vary to any appreci- 

 able extent from that on beef-extract agar. Considerable difficulty has 

 been experienced, however, in keeping this species alive on this agar. 

 It often dies within a week's time. This inability to remain viable on 

 beef -infusion agar was noticed with several different strains of the 

 pathogene. 



Beef-extract agar plates (pH 7.0). Seven-days-old colonies are circular, 

 approximately 3 to 5 millimeters in diameter, glistening, and primulin 



Figure 4. seven-days-old surface and deep colonies of 

 phytomonas phaseoli on beef-extract agar (ph 7.0) 



AT 27° 0. X 2 



yellow in color. The consistency is watery to butyrous. The edges are 

 entire, and their color is not so intense as that of the center of the colony. 



Beef-extract bouillon (pH 7.0). The broth becomes cloudy in twenty-four 

 hours, and very cloudy in forty-eight hours. A yellowish ring is formed, 

 and later a heavy sediment. 



Gelatin slab (pH 6.6). (Temperature 21° C.) Growth occurs along the stab 

 within twenty-four hours. On the second day slight liquefaction may be 

 observed, which proceeds slowly until it is complete in approximately 

 five weeks. Various types of liquefaction occur at different times, with 

 different strains, and in different lots of gelatins. 



Milk. Growth is first observed in about four days, when the medium 

 begins to clear very rapidly. A yellow surface layer is formed, and a 

 more or less heavy sediment appears at the bottom. Within several 

 weeks the upper half of the tube is a clear yellowish liquid, the lower 

 part is cloudy, and a great many tyrosine crystals are formed in the 

 digesting casein. The medium is rendered alkaline. 



