206 
Journal of Agricultural Research 
Vol. I, No. 3 
infection in the field. This being the case, no practical methods of 
control have been undertaken, but in order to determine if possible some¬ 
thing in regard to the way in which the organism gains an entrance into 
the tissue of its hosts, young plants were placed in infection cages in the 
greenhouse and the foliage sprayed with a bacterial solution until it was 
thoroughly wet. This solution was prepared from 5-day-old cultures of 
the organism. Check plants were placed in a control-infection cage and 
sprayed with distilled water. Examination was made at intervals of 
several days, but no diseased spots appeared on either the nasturtium 
or sugar-beet leaves during a period of 20 days. The result of the experi¬ 
ment suggests that infection takes place only in bruised or wounded 
tissue, due to insects or to mechanical 
injury. 
TECHNICAL DESCRIPTION OF THE 
ORGANISM 
Bacterium aptatum, n. sp. 
According to the numerical designations 
adopted by the Society of American Bacte¬ 
riologists, the group number of Bacterium apta¬ 
tum is 211.2322133. 
Form, a short motile rod with rounded ends; 
flagella, bipolar; involution forms rare; no 
spores or capsules observed; pseudozoogloeae 
occur; aerobic; smooth whitish colonies on agar 
plate with fishscalelike markings; clouds beef 
bouillon in 18 to 24 hours; produces alkaline 
reaction in litmus milk, with a gradual sepa¬ 
ration of whey from curd; liquefies gelatin; 
produces ammonia; no reduction of nitrates; 
fluorescence greenish; no diastasic action on 
potato starch; grows in Uschinsky’s and Fer¬ 
mi’s solutions; indol produced after 10 days; 
optimum temperature 27 0 to 28° C.; maximum 
34 0 to 35 0 C.; minimum — i°C.; thermal death point 47.5 0 to 48° C.; vitality 4 
to 10 months in beef agar, 10 to 12 months in bouillon, depending on temperature; 
good growth on litmus-lactose agar; growth much retarded on gentian-violet agar; stains 
readily with basic anilin dyes; not acid-fast; not stained by Gram; tolerates acids; 
oxalic, 0.1 per cent; tartaric, .0.2 per cent; hydrochloric, 0.1 percent; tolerates sodium 
hydroxid in beef bouillon, —18 Fuller’s scale; no growth in Cohn’s solution; killed 
readily by drying; not very sensitive to sunlight; retains its virulence 2 to 3 years; 
pathogenic to nasturtium, sugar-beet, and several other plants. 
COMPARISON OF PSEUDOMONAS TENUIS WITH BACTERIUM APTATUM 
While the work on Bacterium aptatum was being prepared for publica¬ 
tion, Bulletin No. 167 of the Vermont Experiment Station was received, 1 
part 3 of which contains a description of green fluorescent bacteria 
Fig. 5.—Camera-lucida drawing of a portion 
of a cross section of sugar-beet leaf inocu¬ 
lated with Bacterium aptatum . The cells 
containing bacteria were next to many 
collapsed cells. 
1 Hdson, H. A., Jones, C. H., and Carpenter, C. W. Micro-organisms of maple sap. Vermont Agr. Exp. 
Sta. Bui. 167, p. 321-610, 14 fig., 16 pi., 1912. 
