380 Journal of Agricultural Research voi. xiir, no. 7 



South Carolina plants. In South Carolina the stem infection was more 

 prevalent by far than the leaf spotting alone. Bad. viridilividum from 

 the Virginia plants became blue-green on sterile potato cylinders (PI. 

 E, i) the same as Bact. viridilividum from Louisiana (PI. E, 2), but 

 like the Louisiana isolation, the color is fleeting, and frequently there 

 are infectious colonies which will not produce the blue-green color on 

 potato, but which agree in other cultural features. 



Morphological and cultural tests were made with Bact. vitians from the 

 two sources, South Carolina and Virginia, and no doubt remains as to their 

 identity. 



ISOLATIONS AND INOCULATIONvS WITH ORGANISM FROM THE 

 KANSAS LETTUCE 



ISOLATION OF THE ORGANISM 



Pieces of the browned marginal areas from the diseased material 

 from Manhattan, Kans., and of the small irregular reddish spots from 

 the material from Hutchinson were used for isolating. The pieces were 

 immersed in mercuric chlorid (i : 1,000), one test for 2 minutes and 

 another for 3 minutes, washed in sterile water, and mashed up in bouillon. 

 Surface colonies appeared in two days, thin, bluish white, round, shining, 

 some slightly convoluted, most with a smooth surface. The color 

 changes to cream, then yellowish, and the agar becomes a brilliant green. 

 The colonies range from 2 to 7 mm. in diameter when several days old. 



INOCULATIONS 



Inoculations with the organism isolated from the Kansas lettuce 

 were made by spraying water suspensions of young agar cultures on 

 young and half-grown lettuce plants. No wounding was necessary to 

 produce infection. The margins of the inner whorl of leaves became 

 dark brown, almost black, in 24 to 48 hours; the outer leaves were not 

 infected. At first these brown margins were soft, but in a few days 

 they became dry and papery, with a brown discoloration extending 

 farther in the veins and veinlets. This condition had been noted on the 

 infected leaves received from Kansas (PI. 39, A, B). The infected 

 margins were from 0.5 to 1.5 cm. in width, rarely wider. A very tiny 

 curled-up leaf might be entirely browned. Some of the infected places, 

 but not all, first showed as little reddish and brownish spots, and the 

 veins showed darkening before the parenchyma. 



Inoculations were made on plants growing in the open bed and also 

 in pots, which were placed in infection cages where there was plenty of 

 moisture (PI. 40, A, B). Occasionally there would be a plant which 

 resisted infection in the open bed, but scarcely ever one in the infec- 

 tion cage. The temperature of the greenhouse did not seem to have so 



