Mayis, I920 Halo-Blight of Oats 153 



Optimum reaction and toleration umits. — Beef-peptone bouillon 

 was adjusted to each of the following reactions with sodium hydroxid 

 and hydrochloric acid +20, +15, +10, +5, o, —5, —6, —13, —16, and 

 — 22. These were uniformly inoculated from broth cultures and kept 

 at 24° C. At the end of 24 hours there was light clouding in —5,0, +5, 

 and +10. Subsequent clouding occurred in —6 and +15. A stringy 

 precipitate formed in — 13, and on — 15 a thin surface film developed and 

 the medium was slightly darkened. At the end of 48 hours the clouding 

 in + 5 was slightly heavier than in +10, and the flocculent surface film 

 slightly heavier. Clearing began in 3 weeks. At that time +10 was 

 browned, + 15 slightly deeper brown, and +5 and —5 showed a greenish 

 tinge. The optimum reaction for growth is, therefore, + 5 Fuller's scale, 

 although +10 and +15 are also favorable reactions. 



In later tests the limits of growth on agar were +27 and — 17, and in 

 bouillon +27 and — 18, when the agar was reinoculated from an alkaline 

 culture. 



VoIvATilE acids. — Tests for volatile acids were negative. Cultures 

 were grown in tap water containing i per cent Witte's peptone and i per 

 cent dextrose. The steam from these cultures gave an alkaline reaction 

 to litmus although the liquid was acid to litmus. 



Freezing. — Six plates were poured in +15 agar from 24-hour +15 

 broth cultures. This 24-hour culture was exposed for i hour in salt and 

 crushed ice and then six more plates were poured. Eighty-seven per 

 cent of the organisms were killed by this treatment. 



Effect of sunlight. — The organism is sensitive to sunlight; 80 per 

 cent were killed by 15 minutes' exposure on ice in thinly sown beef- 

 peptone agar plates. 



Vitality on culture media. — Typical colonies of this organism have 

 been obtained from +10 beef-peptone agar slants which have stood for 

 II months and from broth cultures 10 months old. These were tested by 

 inoculation on young oat plants and gave abundant and typical halo 

 lesions. 



lyOSS OF virulence. — lyoss of virulence on culture media has not been 

 observed in cultures carried for more than 3 years. 



Group number.' — 221.2323023. 



The name Bacterium coronafaciens, n. sp., is suggested for this organism. 



TECHNICAL DESCRIPTION 



Bacterium coronafaciens, n. sp. 



A motile rod with rounded ends and polar flagella; single, in pairs or long chains, 

 average measurement 2.3 by 0.65 n; no spores, zoogloea, or involution forms ; capsules 

 are formed; slightly facultative anaerobic. On nutrient agar colonies are white, 

 round becoming irregularly circular, flat with slightly raised margins, surface smooth 

 or slightly contoured; deep colonies are lens-shaped and opaque. Its proteolytic 



' SoQETY OF American Bacteriologists, descriptive chart. Indorsed by the society for general use 

 at the annual meeting Dec. 31, 1914. Prepared by the committee on revision of chart identification of 

 bacterial species. 



