The Bacterial Diseases of the Bean 65 



Fermi's solution. A slight clouding appears in twenty-four hours, and 

 in four days there is a very good growth. In a week a pellicle appears 

 which in some cases becomes very heav} r and falls to the bottom of the 

 tube. A green fluorescent pigment appears after several days to a week, 

 and at the end of six weeks this is a water green in color. 



Conn's solution. There is no growth. 



Potato cylinders. At the end of two days there is a very slight growth on 

 the surface of the potato, but no further signs are noticeable. The 

 medium turns slightly gray. 



Cellulose digestion. The organism grows well in the broth, but there is 

 no indication that the cellulose is attacked. 



Starch agar plates (pH 6.6). Plates streaked five or six times, and tested 

 two, six, and ten days after inoculation with a saturated solution of 

 iodine in 50-per-cent alcohol, show no digestion of starch. 



Dextrose broth. The broth in the open arm of a fermentation tube becomes 

 cloudy in twenty-four hours. It is at this time slightly acid, and within 

 four days it is distinctly acid, after which it gradually returns to the 

 alkaline side. A yellow-orange to brown pigment is formed in this 

 medium, which is very marked in one strain. In most cases there 

 appears to be a fair growth in the closed arm of the fermentation tube. 

 No gas is produced. 



Saccharose broth. A light clouding appears in twenty-four hours in the 

 open arm of a fermentation tube. Growth is better on the second day, 

 but there is no growth in the closed arm of the tube. No acid nor gas 

 is produced. 



Lactose broth. A light cloudy growth appears in twenty-four hours and 

 reaches its optimum in four days. No acid nor gas is produced. 



Maltose broth. A cloudy growth appears in twenty-four hours. No acid 

 nor gas is produced. 



Shake agar culture. In beef-extract agar with 1 per cent of glucose (pH 

 7.0), colonies are not found lower than 2 millimeters below the surface. 



Indol production. The bacteria grow well in trytophane broth, and tests 

 for indol at the end of one and of four days with the Ehrlich-Bohme 

 method have been negative. 



Nitrate reduction. Good growth occurs in nitrate broth, and tests for 

 nitrites made at the end of two, four, and eight days with sulfanilic acid 

 and a-napthalamine in acetic acid show no presence of nitrites. A posi- 

 tive test was obtained on the above medium with Escherichia coli. 



Hydrogen-sulfide production. Growth appears on Wilson's medium within 

 three or four days, but there is no positive reaction. On lead-acetate 

 agar there is a faint browning along the stab. The bacterial mass at 

 the surface appears rather blue-green in color. 



Chromogenesis. Several kinds of pigments are produced by this organism 

 on various media. A green fluorescent pigment, which is water-soluble, 



