Dec. 13, 1915 
Angular Leaf-Spot of Cucumbers 
469 
made. Some months later (September, 1915) in a similar experiment 
two out of four inoculated fruits became soft-rotted. These fruits were 
from the market. All four showed the local gumming at the point of 
inoculation (needle pricks) after five days, while check pricks gave no 
gumming. Two days later two fruits began to soften, and the next day 
the whole interior was swarming with bacteria. Plates were poured from 
the interior of one of these fruits under sterile conditions, and again only 
spreading fimbriate colonies were obtained. Smears from these colonies 
stained by Van ErmengenTs flagella stain gave rods with as many as 8 
or 10 peritrichiate flagella. This organism grew well in the depths of 
agar stabs and curdled milk with reddening of litmus in milk. The 
other two inoculated fruits remained sound and after two weeks when cut 
open showed only a very local infection not extending much beyond the 
needle pricks in any direction. 
Since the organism causing the leaf-spot is polar flagellate and aerobic, 
does not develop a fimbriate growth on agar, and does not curdle milk 
or redden litmus in milk, it is evident that this soft-rot was due to an 
intruder, which may have come from the surface of the fruits, since they 
were not sterilized, but only washed. 
When these fruits became soft-rotted, the suspicion arose that possibly 
the softening and cracking of the stems and petioles (PI. XLV, fig. 2) 
might also have been due to some unsuspected soft-rot organism. The 
inoculation experiments with Bad. lachrymans were therefore repeated 
on stems and petioles of free-growing cucumbers with the same result as 
before—i. e., softening and cracking of the younger stems and petioles. 
From one of these stems platings were made and Bad . lachrymans 
obtained in pure culture. At the same time several control inoculations 
were made on stems and petioles, using a subculture of the fimbriate, 
peritrichiate, soft-rot organism plated from one of the softened cucumbers 
above mentioned, but no rot occurred (four weeks). * This organism, how¬ 
ever, soft-rotted green cucumber fruits when inoculated by needle pricks. 
Last of all, following the discovery of Traverso’s paper, another set 
of inoculations was made on cucumber fruits. Six marketable green 
hothouse fruits were selected and inoculated with Bad. lachrymans . At 
the end of 10 days in culture dishes at temperatures varying from 24 0 
to 30° C. all showed local gumming and infection about the needle 
wounds, but none of them developed any soft-rot (PI. XLVI, fig. 3), 
HISTOLOGY OF DISEASED LEAVES 
Pieces of a leaf that showed spotting were fixed on the second day, 
embedded, sectioned, and stained. Stomatal infections were very 
numerous (PI. XLVII, fig. 1). The bacteria gorged the opening of the 
stoma in some cases, as well as the cavity beneath it. Even a.t this 
early date the bacteria had spread in great numbers for some distance 
from the stoma, crowding apart or crushing the cells of the parenchyma 
and causing a slight swelling on the leaf (PI. XLVII, fig. 2). 
