290 THE AMERICAN NATURALIST. (VoL. XXXII. 
but perhaps true branching occurs in some species closely related to 
this organism. Motile masses are never produced by the Ascomy- 
cetes, a difference that constitutes a valid point of separation. 
Meyer discusses the relationship of Schizomycetes to this group, and 
proposes the following classification of the 
BACTERIACE2. 
BACTERIE&. Cells motionless. Bacterium. 
BACILLE&. Flagella arising from the whole surface. Bacillus. 
PSEUDOMONATE. Flagella polar. 
(a) Normally with a single flagellum. Pactrineum. 
) Normally with more than one flagellum. Bactrilleum. 
ASTASIE&. Flagella in groups, lateral. 
Flagella in one or two groups, one-celled rods. Aszasza. 
L. H. PAMMEL. 
Brown Rot of Cruciferous Plants. — Erwin F. Smith, who has 
made an exhaustive and careful study,’ concludes that Pseudomonas 
campestris is responsible for the brown rot of cabbage and other 
cruciferous plants. There certainly seems to be no doubt that the 
organism described somewhat briefly by the writer several years ago 
is identical with that described by Smith. It produces a distinct 
browning in the bundles, the bacteria having a fondness for the 
alkaline sap of the bundles and little attraction for the acid paren- 
chyma. Infections were obtained by needle punctures, by means of 
slugs and insect larve, and through the water pores situated on the 
teeth of the leaves. Infections through ordinary stomata were not 
obtained ; the waxy bloom on the cabbage leaf protects the plant. 
It is probable that a majority of the natural infections in the field 
take place above ground, the disease being transmitted from diseased 
to healthy plants and from one part of a plant to another, as the 
result of the visits of insects and other small animals. The organism 
grows well in feebly alkaline beef broth. Gelatin is slowly liquefied. 
In addition to these media, Smith cultivated it on cabbage broth, 
litmus cabbage broth, agar, potato, carrot, beet, onion slices, orange 
segments, cocoanut flesh, etc. In cruciferous substrata it grew 
promptly and with great vigor, except on the horse-radish, where the 
growth at first was slow. On steamed cauliflower the organism was 
brightest, approximately lemon yellow or light cadmium; it was 
1 Erwin F. Smith, Pseudomonas campestris hacen The Cause of a Brown 
Rot in Cruciferous Plants. Centralb. f. Bakt. u. Parasitenk. Abt. ii, Bd. iti, 
pp- 284-291, 408-415, 478-486, Pi. VI. 1897. 
