574 BACTERIA OF PLANT DISEASES. 



gamboge, chrome yellow, or canary yellow, but sometimes paler. Old 

 cultures on some media darken from the production of a soluble, pale-brown 

 pigment. This feeble brown stain is best developed in hyacinth broth, in 

 potato broth with peptone, on turnips, on radishes, and on banana rinds. It 

 was not observed in acid or alkaline beef broth, on cocoanut flesh, on sugar 

 beets, in nutrient starch jelly, in agar, or in gelatin., with or without sugar. 

 This organism grows readily on potato cylinders standing in distilled water, 

 but it never becomes copious or fills the water with a solid yellow slime, 

 owing to its feeble diastatic action. Potatoes on which it has grown, even for 

 several months, always give a strong starch reaction with iodine. It behaves 

 the same on nutrient sta.rch jelly free from assimilable sugars. It liquefies 

 nutrient gelatin and Loffler's blood serum, but does so slowly, and will not 

 liquefy gelatin at all if ten per cent cane sugar is added. Growth on 

 nutrient agar or nutrient starch jelly is inhibited (unless the inoculation be 

 from a solid culture and very copious) by the addition of ten per cent 

 glycerol, and is greatly retarded by five-per-cent glycerol; even two and a 

 half per cent of glycerol retarded growth. Growth in beef broth was much 

 retarded by the addition of 1.5-per-cent sodium chloride. Organisms ex- 

 tremely sensitive to plant acids, including those of the hyacinth. Aerobic ; 

 doubtfully, if ever, facultative anaerobic; not a gas producer. Does not 

 redden litmus milk, but makes it bluer, and slowly separates the casein from 

 the whey by means of a lab ferment. Produces under some circumstances, 

 and slowly, a small amount of non-volatile acid (slime acid ?) with various 

 sugars (grape, cane, etc.), which acid is frequently obscured by the moderate 

 production of alkali. In the presence of air produces an organic acid 

 (probably acetic) from ethyl alcohol dissolved in milk or bouillon. Inverts 

 cane sugar, but apparently without the intervention of any enzyme. Will 

 not grow on thirty-per-cent grape-sugar agar. Resists dry air very well, i.e., 

 more than forty -eight days when spread on cover glasses in thin layers. 



" In Dunham's solution with methylene blue the color is reduced in a 

 few days, but re-oxidizes quickly on shaking ; final color (fifty- six days) bright 

 blue. In Dunham's solution with indigo carmine the color changes to a 

 bright blue, which persists for a long time ; final color yellowish. In Dun- 

 ham's solution with rosolic acid and enough HC1 to render the fluid yellow- 

 ish, Ps. hyacinthi did not redden the fluid, but made it colorless, the bac- 

 terial precipitate becoming rosy or salmon-colored. Produces indol slowly 

 in peptonized beef broth and in peptonized Uschinsky's solution ; does not 

 produce nitrites in these solutions. Does not reduce potassium nitrate to 

 nitrite in peptonized beef bouillon. Not a strong-smelling germ. Not 

 readily destroyed by its own decomposition products except in media contain- 

 ing alcohol. 



' ' Will not grow in the thermostat at 37 C. , and grows very feebly 011 

 some media and not at all on others at 34 to 35 C. Optimum temperature 

 28 to 30 C., or thereabouts. Minimum temperature approximately 4 C. 

 Thermal death point (ten minutes' exposure), 47.50 C. ; nearly all the rods 

 are killed at 47 and a great many at 46.50 C. Did not grow at room tem- 

 perature after six days' exposure in alkaline beef broth in the thermostat at 

 35 to 36.35. Does not grow well in Uschinsky's solution. Grows much 

 better in Uschinsky's solution when peptone is added to it. Grows well 

 with a bright yellow color on cylinders of steamed cocoanut flesh, standing 

 with one end in distilled water. 



"Pathogenic to hyacinths. Enters the plant through wounds, through 

 the blossoms, etc., and multiplies in the vascular system, filling the vessels, 

 especially those of the bulb, with a bright yellow slime consisting of bacteria. 

 The walls of the vessels are destroyed and extensive cavities are formed in 

 the bundles. The parenchyma around the bundles is also involved, but only 

 very slowly, the organism being a feeble destroyer of cell walls. The host 

 plant is not rapidly destroyed, a year or more being necessary. The cells 

 are first separated by solution of the middle lamella, but the wall itself seems 



