YELLOW DISEASE OF HYACINTHS. 



349 



Fig. 146.* 



to +40 (lactic acid). Growth was retarded decidedly by +30 bouillon (to the i8th 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, c. g., coconut-cylinders (fig. 146'), but notwhen kept over others.e.g., potato-cylinders, 

 turnip-cylinders (fig. I46 2 ). 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 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 (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 i, fig. 12). Streaks on 

 sugar agars sometimes developed the surface shown in 

 fig. 148. 



The best growth in gelatin was in that made o on 

 Fuller's scale. 



The growth in gelatin slightly acid or slightly alka- 

 line to litmus was not nearly so good; growth was good, 

 however, in o gelatin to which a small amount of malic 

 acid was subsequently added (+48 and +54 with 5 and 

 10 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) 



Fig. 147. f 



*Fio. 146. Production of hydrogen sulphide by Bad. hyacinthi: i, Lead acetate paper exposed (and browned) 

 over culture on coconut flesh; 2, the same after exposure over cultures on potato or carrot. 



fFio. 147. Strips of Petri-dish agar-poured-plates of Bad. hyacinthi, showing slow growth of the colonies: a was 

 photographed at end of 16 days at about 23 C.; b was poured Nov. 13, 1906, in + 15 peptonized beef-bouillon, i per 

 cent agar, incubated at 15 to 20 C., and photographed Dec. 25. Room temperatures. 



