^4 BACTERIA IN RELATION TO PLANT DISEASES. 



Effect of Acids. Bacterium stewarti is rather resistant to acids. It tolerates much more of lactic, 

 malic, or tartaric acid than Bad. hyacinthi. (See observations under growth in acid plant juices, etc.) 



Dry Air. The relative resistance to dry air is not known. Its resistance is probably con- 

 siderable. 



Sunlight. Stewart exposed a portion of an agar-poured plate to bright sunlight for 3 hours, 

 nearly all of the organisms being destroyed. Under the covered portion colonies came up thickly in 

 4 days at 23 C. The writer has made no experiments. 



Effect on Animals. The organism is not known to be pathogenic to animals. The writer has 

 made no experiments. It is frequently fed in great quantity to cows (in corn stalks) . 



Additional cultural tests were made in 19 13 with the following results: 



Beef bouillon over chloroform: Growth retarded for some days, but after two weeks about equal 

 to growth in ordinary bouillon. 



Alkaline peptone beef-bouillon ( 40 stock .5700, 35 stock 5792, and -30 stock 5791: No 

 growth (Jan. 18, Feb. 24, April 3, May 28). The tubes were inoculated heavily both from agar and 

 bouillon. 



Cabbage juice ( + 17): A good growth. After several months a copious, dirty yellow, moder- 

 ately alkaline growth, free from crystals (May 28). 



Tomato juice (+60): No growth. 



Cohn's solution: No growth in 6 weeks. 



Uschinsky's solution: A good growth. 



Asparagin (2 per cent in distilled water): No growth in 3 months. 



Asparagin (2 per cent in river water) : Slight growth after 1 1 days in tubes heavily inoculated 

 from agar cultures; none in 2 months in tubes inoculated from peptone beef-broth cultures. 



Peptone water (stock 5705, 2 per cent Witte's) : Growth. No indol reaction after 10 days; 

 slight indol reaction after 22 days. Tested with sodium nitrite and sulphuric acid. 



Cane-sugar with asparagin (stock 5704): Growth in 2 tubes out of 10 after 2 months. 



Temperature: Thermostat 24 hours at 27 to 28 C. Good clouding. 



Ice box, compartment 6 (temperature 14 to 14.5 C). Clouded in 48 hours and cleared in 14 

 days. In compartment 5 (temperature 8.4 to 12 C., average about io C.) zoogloea? visible in 8 

 to 10 days. Not then clouded, but a faint clouding after 22 days. In compartment 4 (temperature 

 8 to ii C.) slight clouding in 29 days (McCulloch strain); in 39 days (Galloway strain). In com- 

 partments 3 to 1 (temperature 6.5 to io C, 3.7 to 5.4 C, and 0.9 to i.5C. respectively), no cloud- 

 ing or zoogloese in 39 days, but when removed to room temperature the tubes clouded in less than 

 7 days. 



RESUME OF SALIENT CHARACTERS. 



POSITIVE. 



Yellow organism causing a vascular disease of maize, especially of sweet corn; short 

 rod with rounded ends, generally less than 4X1/J, often 1 to 2^X0.5 to 0.7^; occurs singly, 

 in pairs or fours, joined end to end, or as small pseudozoogloeae (in various media) ; motile by 

 means of a polar flagellum (sometimes more than one is present) ; stains readily with various 

 anilin dyes, often not uniformly with carbol-fuchsin ; very slow growth in gelatin, surface- 

 growth dense, rather dry, slightly roughened, bright buff-yellow; good bright buff-yellow 

 growth on Loeffler's blood-serum; slow growth on agar plates, forming small, round, yellow, 

 surface colonies, buried colonies very small; smooth, translucent growth on agar streaks, 

 frequently lobed on the margins; jagged X-shaped or prismatic crystals often present in 

 old agar-cultures ; good growth whole length of the stab in stab-cultures in agar; good 

 growth in nitrate agar, whitish at first; very feeble growth on silicate jelly (Fermi's solu- 

 tion) ; moderate amount of yellow growth on potato cylinders accompanied by graying of 

 the potato; very little action on potato starch; moderate buff -yellow growth on coconut 

 cylinders ; thin buff -yellow slightly iridescent growth on cylinders of yellow turnip ; growth 

 on rutabaga resembling that on turnip; excellent deep buff-yellow growth on sugar-beet 

 cylinders; feeble whitish rim and pale yellow precipitate in peptonized beef-bouillon which 

 becomes well clouded; prolonged and copious growth in cabbage-leaf juice titrating +40; 

 growth in tomato-fruit juices (titrating +55, +59, and +64, Fuller's scale) was retarded 

 at first but later was prolonged and copious; good growth in potato broth titrating +30, 



