nee ag Oe nT 
350 BACTERIA IN RELATION TO PLANT DISEASES. 
gelatins. Cane-sugar added to the gelatin favors long continued growth, especially if the 
- medium is quite alkaline on the start. 
Minimum temperature for growth approximately 4° C.; optimum temperature 28° to 
30° C.; maximum temperature approximately 34° to 35° C. Bact. hyacinthi will not grow 
in the thermostat at 37° C., and growsveryfeebly on some media and not at all on others at 
34° to 35° C. Thermal death point 47.50° C., most of the rods are killed at 46.50° C. 
Good media for long continued growth are litmus-milk, sugar-beet cylinders in water, 
and nutrient gelatin neutralized to phenolphthalein with sodium hydrate and then acidified 
with malic acid (+50) and dosed with 5 per cent cane-sugar. The vitality on culture- 
media (except at high temperatures) usually varies from 3 or 4 weeks to as many months, 
156 days and 174 days being the oldest viable cultures observed; these vigorous old cul- 
tures were on —30 gelatin, and on o gelatin with 10 per cent cane-sugar and malic acid to 
read +54 of Fuller’s scale, the temperature ranging from 10° to 25° C. 
The slow development of the parasite in the host plant is attributed 
to its feeble action on cell-walls, its feeble action on starch, its sensi- 
tiveness to acids, and its strict aerobism. 
RESUME. OF SALIENT CHARACTERS. 
POSITIVE. 
Pathogenic to Hyacinthus orientalis causing a yellow disease of 
the vascular system and finally a decay of the bulbs; a short motile 
rod, single, in pairs or 4’s end to end, with rounded ends and one polar 
flagellum (chains and filaments in sugar-rich media) ; pseudo-zoogloee 
and involution forms; stains readily from young cultures in basic 
anilin dyes; bright yellow in the host plant and on media; a slow 
grower; surface colonies flat, roundish, smooth, wet-shining; aerobic; 
inverts cane-sugar; slowly liquefies nutrient gelatin and Loeffler’s soli- 
dified blood-serum; liquefaction of gelatin prevented by addition of 
cane-sugar in sufficient quantity; dissolves middle lamella in hyacinth, 
and softens it in turnip and carrot, but only very slowly; produces a 
non-volatile acid in small quantities from grape-sugar, fruit-sugar and 
cane-sugar, and a volatile acid and probably also an ester (steam 
fragrant) from ethyl alcohol; grows well in milk, forming a bright 
Fig. 148.* yellow rim and tyrosin crystals, leucin (?); blues litmus milk, pre- 
cipitating the casein (by means of a lab ferment) as a mobile fluid 
which settles slowly and becomes partially peptonized—tyrosin crystals appear slowly; 
growth on potato-cylinders not long continued nor very copious (iodine-starch-reaction 
always present, i. ¢., diastasic action feeble); tolerates sodium hydrate to beyond — 20 
on Fuller’s scale, also tolerates malic acid in beef-bouillon to about +30 and lactic 
acid to about +40; growth very slow on nutrient starch-jelly, much improved by addition 
of diastase; growth retarded by glycerin and by large doses of grape-sugar (9 per cent), 
or cane-sugar (17 per cent); streaks on the sugar-agars (9 to 23 per cent) were dry (not 
syrupy) and were variously areolated, reticulated, wrinkled or shagreened; growth feeble 
in Uschinsky’s solution, better with peptone added; dextrin stimulates growth; sensitive 
to sodium chloride and to acids, e. g., lactic, oxalic, acids of gelatin, growth retarded in 
hyacinth-juice and in other acid plant-juices; grows slowly and with much difficulty in 
bouillon over chloroform; moderate development of hydrogen sulphide; reduces litmus 
slowly; methylene bluwe in Dunham’s solution reduced, final color bright blue; indigo-— 
carmine in Dunham’s solution becomes bright blue; rosolic acid in Dunham’s solution 
becomes colorless and the bacterial precipitate is stained; acid fuchsin in Dunham's 
*Fic. 148.—Shagreen surface of Bact. hyacinthi on slant agar containing much cane-sugar. 
