. Bacteria in relation to plant diseases. Bacteriology; Plant diseases. YELLOW DISEASE OF HYACINTHS. 349 Fig. 146.' to +40 (lactic acid). Growth was retarded decidedly by +30 bouillon (to the iSth day or longer). This organism produces indol in peptonized beef-broth or peptonized Uschinsky's solution, but not so abundantlyas Bacillus coli. Lead acetate paper was browned, indicating slow evolution of hydrogen sulphide, when kept in the top of the test tube over certain cul- tures, e. g., coconut-cylinders (fig. 146'), but notwhen kept over others, e. g., potato-cylinders, turnip-cylinders (fig.
. Bacteria in relation to plant diseases. Bacteriology; Plant diseases. YELLOW DISEASE OF HYACINTHS. 349 Fig. 146.' to +40 (lactic acid). Growth was retarded decidedly by +30 bouillon (to the iSth day or longer). This organism produces indol in peptonized beef-broth or peptonized Uschinsky's solution, but not so abundantlyas Bacillus coli. Lead acetate paper was browned, indicating slow evolution of hydrogen sulphide, when kept in the top of the test tube over certain cul- tures, e. g., coconut-cylinders (fig. 146'), but notwhen kept over others, e. g., potato-cylinders, turnip-cylinders (fig. 146'). In most cases, if the culture-medium developed the brown stain the sensitive paper remained unstained; if the culture remained free from the brown pigment the lead acetate paper was darkened. The only exception noted was }'ellow globe turnip: here both paper and substratum were browned. Nitrites are not produced from organic nitrogen (beef-broth, peptone), nor from potassium nitrate in peptonized beef-broth. This organism is not a strong smelling germ. It is not readily destroyed in ordinary culture-media by its own decomposition products nor in mixed growths. It grows well with a bright yellow color and-without retardation on steamed coconut-flesh, standing in distilled water. On this medium in a scanty air-supply fin vacuo, mercury at 3 inches) the growth was paler yellow than on the checks (bulk for bulk, examined on white paper); the same result was obtained on potato. In agar and gelatin the growth is best toward the surface of the stabs. A whitish chemical halo forms slowly on the surface around the bacterial growth; this is soluble in acids, and does not appear when grape-sugar or cane-sugar is added. Growth does not occur in an atmosphere of pure hydrogen, nitrogen, or carbon dioxide, and exposure to these gases retards subsequent growth in the air, or prevents it altogether, if the exposure is longer than a few days. The organism is more tole- rant of these gas
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