YELLOW DISEASE OF HYACINTHS. 349 
to +40 (lactic acid). Growth was retarded decidedly by +30 bouillon (to the 18th day 
or longer). ; 
This organism produces indol in peptonized beef-broth or peptonized Uschinsky’s 
solution, but not so abundantly as 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, ¢. g., coconut-cylinders (fig. 146'), but not when kept over others, ¢. 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 yellow globe turnip: here both paperand 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 Fis. 146." 
steamed coconut-flesh, standing in distilled water. On this medium in a 
seanty air-supply (in 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 gases on some media than on others, e. g., 
subsequent growth in air after 10 days’ exposure to car- 
bon dioxide was retarded in beef-broth, but not on 
coconut cylinders. Growth in vacuo is feeble or alto- 
gether wanting, according to the completeness of the 
exhaustion of the air. 
Buried colonies in agar and gelatin are small, grow 
slowly, and show no strong tendency to break through to 
the surface. Surface colonies on agar and gelatin are 
round, smooth, wet-shining, pale yellow with a thin dis- 
tinct margin and are not rounded up much. They grow 
slowly (fig. 147, and Bull. 26, plate 1, fig. 12). Streaks on 
sugar agars sometimes developed the surface shown in 
fig. 148. 
The best growth in gelatin was in that madeo on 
Fuller’s scale. 
The growth in gelatin slightly acid or slightly alka- 
line to litmus was not nearly so good; growth was good, 
Fig. 147.4 however, in o gelatin to which a small amount of malic 
acid was subsequently added (+48 and +54 with 5 and 
Io per cent cane sugar). Growth was very poor on acid and alkaline peptonized beef-broth 
gelatins (+40 and —20). Streak cultures came up slowly, even on the best (10 per cent) 
*Fic. 146.—Production of hydrogen sulphide by Bact. hyacinthi: 1, Lead acetate paper exposed (and browned) 
over culture on coconut flesh; 2, the same after exposure over cultures on potato or carrot. 
{Fic. 147.—Strips of Petri-dish agar-poured-plates of Bact. hyacinthi, showing slow growth of the colonies: a was 
photographed at end of 16 days at about 23° C.; 6 was poured Nov. 13, 1906, in +15 peptonized beef-bouillon, 1 per 
cent agar, incubated at 15° to 20° C., and photographed Dec. 25. Room temperatures. 
