348 



BACTERIA IN RELATION TO PLANT DISEASES. 



strict aerobe, except in the presence of maltose or some unknown substance sometimes 

 contaminating the maltose; a matter open to further inquiry. Cane-sugar is inverted. 

 Oxydase and peroxydase are absent, i. c, cultures give no reaction with guaiac resin 

 in alcohol, nor on addition of hydrogen peroxide. Tyrosinase perhaps occurs, i. c, 

 the substance causing the brown stain. Catalase is present, i. e., some body yielding a 

 copious evolution of gas when hydrogen peroxide is added to old potato cultures. This 

 substance is destroyed at 85 C. 



Large doses of grape-sugar or cane-sugar in slant agar retard growth at first (9 per 

 cent grape, 17 per cent cane) and then stimulate it greatly. On 10 grams of recently slanted 

 nutrient agar containing 3 grams of grape-sugar no growth was obtained. 



A small amount of non-volatile acid is developed out of various sugars grape-sugar, 

 fruit-sugar, cane-sugar, galactose, maltose; and in old cultures on the following substrata: 

 carrot ( occasionally), rutabaga, sweet potato, sugar-beet. 



The steam from old cultures in hyacinth-broth caused a 

 copious rusty precipitate when conducted into Nessler's 

 solution, indicating the presence of ammonia or amins. 



This organism grows readily on all ordinary culture- 

 media except when it is too salt or too acid. It is very sensi- 

 tive to acids, even those in the parenchyma-juice of the 

 hyacinth retard growth (clouding) decidedly (14 days, 16 

 days, or more). Growth did not take place in potato-broth 

 ( + 30), in juice of slow-growing cabbage leaves (+49), cauli- 

 flower-broth, sugar-beet juice diluted with water, or juice of 

 green or ripe tomato-fruits ( + 59 and +64) ; growth was also 

 much retarded in acid beef -broth ( + 40). The bacterium 

 would not grow in beef -broth concentrated by boiling ( +80). 

 When the acidity of the +30 potato-broth was reduced 

 slightly ( + 28, +26), by sodium hydrate, growth took place. 

 Growth in beef-broth was retarded (5 to 7 days) by 1.5 

 per cent c. p. sodium chloride. 



It does not grow well in Uschinsky's solution; in this 

 medium there was either no growth or it was long delayed and 

 feeble (and without much yellow color) unless peptone was 

 added to it, in which case growth was centupled. 



Methylene blue in Dunham's solution was reduced 

 within a few days, but reoxydized quickly on shaking, and 

 was bright blue on the death of the organism, the bacterial 

 precipitate being unstained. Indigo carmine in Dunham's 

 solution changed from a dull blue to a bright blue and retained this color for a long time, 

 but finally became yellowish. Rosolic acid in Dunham's solution with enough c. p. hydro- 

 chloric acid to render the medium yellowish did not redden but became colorless; the bac- 

 terial precipitate, on the contrary, became rosy or salmon colored. Acid fuchsin in Dunham's 

 solution bleached slowly, the color being all gone in about 4 weeks. Litmus in various 

 media was bleached very slowly, the reduction being evident usually only at the close of 

 the second or third week. 



The optimum alkalinity for growth in peptonized beef-bouillon lies between o and +15 

 of Fuller's scale; the maximum tolerated alkalinity (sodium hydroxide in bouillon) is more 

 than 20 and less than 40; in bouillon the tolerated acidity is about +30 (malic acid) 



Fig. 145. 



'Fig [45. Behavior of Bact. hyacinthi in a fermentation-tube containing water, 1 per cent Witte's peptone, and 

 1 m maltose (the latter 3 times recrystallized). Culture cloudj in open end and clear in closed end alter S days 

 Drawn Oct. is. [906. 



