WILT OF CUCURBITS. 269 
pricks to the margin. The ninth day (2 p.m.) the wilt involved most of the pricked side of the leaf 
(fig. 75) and 25 hours later all of the pricked leaf had wilted but the petiole, while the other leaves 
were normal. The eleventh day all the leaves had collapsed. The sixteenth day the vine had 
shriveled to the ground. 
(277.) Cucumis melo var. dudaim. This was a small plant. Many pricks were made on the 
blade of one leaf. The sixth day (10 a. m.) there was a slight wilt and change of color in the center 
of the pricked area. Twenty-four hours later two-thirds of the pricked leaf was drooping. The eighth 
day the pricked leaf was turgid with the exception of a wedge-shaped area extending from the pricks 
to the tip and involving about one-eighth of the blade (fig. 75). The next afternoon there was only 
a little increase of the wilt, but 25 hours later all of the blade 
of the pricked leaf was wilted. The petiole was still turgid. 
The blades of the first three leaves up now showed a slight 
droop. The twelfth day all the leaves had collapsed and the 
sixteenth day the vine had shriveled to the earth. 
(278.) Benincasa cerifera. Many pricks were made on one 
of the leaf-blades of a small plant. On March 3 there were 
no signs, but 24 hours later there seemed to be a slight droop . 
of the pricked portion. On March 5 there was no clear evi- 
dence of the wilt, but the following afternoon (end of the eighth 
day) there was change of color and distinct wilt. These 
signs were confined to an area of about 1 sq. cm. from the ; 
pricks to the tip, and the most of the pricked leaf was still Fig. 75.* 
normal. ‘Twenty-five hours later the wilt was spreading slowly 
in the blade of the pricked leaf. The twelfth day six leaves besides the pricked one (part above it 
and part below) were wilted, some badly. Four days later the vine had shriveled to the ground. 
(279.) Watermelon (Citrullus vulgaris), This was a small plant. Many pricks were made on 
one leaf-blade. On March 3, at 10a. m., there were no signs of the wilt, but 24 hours later the pricked 
leaf had changed color and wilted from the pricked area outward to the tip, about one-third of the 
leaf being affected. The following day the leaf had recovered its turgor except a very small wedge 
at the tip beyond the pricks. The bulk of the pricked area seemed normal. ‘The next afternoon 
there was no decided increase. During the next 25 hours there was a slow spread of the wilt and 
change of color (whiter) in the blade of the pricked leaf. Two 
days later about one-fourth of the pricked leaf had wilted and 
dried out. The rest was normal. Up to the seventeenth day 
there was no change. Four days later the whole of the blade of 
the pricked leaf, which was a small one, had wilted. The petiole 
and remainder of the plant were normal. 
(280.) Cucurbita californica. Many pricks were made on one 
leaf-blade which was 2 inches across. ‘The leaf was almost exactly 
the shape of a leaf of English Ivy. On March 3, at 10 a. m. there 
was a slight wilt in the pricked area. ‘Twenty-four hours later 
about one-third of the pricked leaf had wilted and the following 
morning fully one-half of the inoculated leaf had succumbed to 
the wilt (see fig. 76). The next afternoon (March 6) the whole 
of the pricked leaf had collapsed, also the first leaf below, the 
neighboring cotyledon, and the first three leaves above. The 
stem was turgid as were also the fourth and fifth leaves up and 
Fig. 76.t the other cotyledon. ‘T'wenty-four hours later the signs were 
much aggravated. The twelfth day the leaves had collapsed 
including the petioles and the terminal part of the stem. The plant was now removed and put into 
alcohol. On microscopic examination great numbers of bacteria were found in the vascular bundles 
of the stem. 
(281.) Datura stramonium. This was a young thrifty plant. Many pricks were made on a leaf- 
blade. A great quantity of bacteria were put into the leaf, but up to the twenty-first day the plant 
was growing finely and there were no signs of the wilt. 
*Fic. 75.—Left: Leaf of plant No. 276 (Cucumis melo var.dudaim), ninth day after inoculation with Bacillus 
tracheiphilus, shaded part wilted. Right: Leaf of inoculated plant No. 277 (Cucumis melo var. dudaim) on eighth day 
after Bacillus tracheiphilus was introduced by needle-pricks. The first wilt was a little earlier (central dark shading). 
+Fic. 76.—Leaf of Cucurbita californica (plant No. 280) inoculated with B. tracheiphilus. The needle-pricks were 
made Feb. 26, 1896, and the wilt appeared in the deeply shaded part March 3. During the next two days it involved 
over half the leaf-blade as shown by the lighter shading. The whole plant collapsed on the twelfth day. 
