374 Journal of Agricultural Research voi. xiii, No. 7 



plates were poured. The surface colonies appeared in from two to four 

 days. They are at first a light-cream color, round, wet-shining, with 

 fine surface markings. The margin is entire, with light and dark areas 

 in an hourglass arrangement when viewed by transmitted light. When 

 older, the colonies are yellow, without surface markings (PI. 35, C). 



Inoculations were made by spraying mature lettuce plants with pure 

 cultures of the bacterium suspended in water (24- to 48-hour agar slants 

 washed off in sterile water) and by pricking some of the leaves with a 

 sterile needle. Those leaves of the older plants which were punctured 

 became infected readily. Inoculations were made also by smearing the 

 bacterial slime on the leaves and stem, and then puncturing the smeared 

 places with a fine sterile needle (PI. 36, A, B). Plants beginning to 

 head or already headed became diseased readily, and those about to send 

 up a seed stalk always showed the worst infection (PI. 36, D, K). 

 Young plants were only slightly affected, and usually recovered. Plants 

 sprayed but not punctured rarely became infected. Repeatedly inocula- 

 tions were made successfully; then the organism was reisolated; the 

 reisolation colonies proved likewise to be infectious. The original colony 

 kept growing on artificial ]piedia was still infectious a year after isolation. 



The organism was inoculated into cabbage {Brassica oleracea capitata) 

 in order to compare it with inoculations with Bacterium campestre. No 

 infection followed with the lettuce organism, but Bact. campestre infected 

 the cabbage readily. It was thought, too, that this lettuce organism 

 might prove infectious to the heart of celery ; therefore inoculations were 

 made twice into young plants by spraying and by punctures, but with 

 negative results. Nearly mature celery plants were treated in the same 

 way with the same results. 



DESCRIPTION OF THE SOUTH CAROLINA ORGANISM 



The organism is a bacterium, a short rod with rounded ends, occurring 

 singly or in pairs, occasionally in short chains. In stained host tissue 

 the measurements of single rods vary from 0.62 to 1.04 jjl long, and 0.42 

 to 0.83 ft wide (PI. 41, A). Grown for one day on beef agar and 

 stained with Loeffler's flagella stain, they vary from 0.62 to 1.24 /x long 

 and 0.42 to 0.83 n wide. 



The organism is not actively motile; often in the sections of fresh 

 tissue in which the bacteria occurred in numbers very little or no motion 

 could be detected on microscopical examination. The motility was 

 demonstrated better in young agar cultures. The flagella are polar, 

 varying from one to several at each pole, but most commonly one at 

 one pole. They were stained by Casares-Gil's flagella stain (PI. 41, B). 



Capsules were stained by Van Ermengem's flagella stain. The absence 

 of spores was tested by staining and also by heating old live bouillon 

 cultures. The tests were negative. 



