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. liyacinthi will not grow 

 in the thermostat at 37° C, and grows very feebly 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 -f 54 of Fuller's scale, the temperature ranging from 10° to 25° C. 

 The slow dcA'clopment 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. 

 Po.srnvE. 



Pathogenic to Hyacinlhiis 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-zoogloese 

 and inA'olution forms; stains readily from young cultures in basic 

 anihn 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 hquefies nutrient gelatin and Loeffler's soh- 

 dified blood-serum; Hquef action 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 

 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-cyhnders not long continued nor very copious (iodine-starch-reaction 

 always present, i. e., diastasic action feeble); tolerates sodium hydrate to beyond 

 on Fuller's scale, also tolerates malic acid in bee:" '. : l'-^- -. ,:: .-l-..- -_. -- 



acid to about +40; growth very slow on nutrient st£ . ., ,. ;. , 



of diastase; growth retarded by glycerin and by latHe caoses is «r^-l^-[^ ■■'•-; n -nvr 

 or cane-sugar (17 per cent); streaks on the sugar-a,.. 

 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, oxaHc, acids of gelatin, growth retarded in 

 hyacinth-juice and in other acid plant-juices; grows slowly and withmuch difflculty in 

 bouillon over chloroform; moderate development of hydrogen sulphide; reduces litmus 

 slowly; methylene blue 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 



F,g. 148.' 



20 

 c 

 n 



), 

 ...ot 



*FiG. 148. — Shagreen surface of Bad. hyacinthi on slant a. 



agar conUuning much cane-sugar. 



