WILT OF CUCURBITS. 253 
they were lower down than the blade of the second leaf which was wilted. The tenth day the petioles 
were still rigid but all the blades were drooping except of one cotyledon and on the tiny leaves of the 
bud which were not transpiring much. ‘The fourteenth day all the leaves were wilted. The petioles 
and stem were still bright green and turgid. 
The plant was now examined microscopically. The vessels were gorged with the bacillus and 
there was an extensive degeneration of the spiral vessels and of the primary vessel-parenchyma 
(slide 210). Portions of this vine were preserved in three different ways to determine the best way 
to fix the bacilli and slime in the vessels without shrinkage of the tissues of the host: (1) The first 
lot was put directly into absolute alcohol which began to remove the chlorophyll inside of two hours 
so that the lower half of the fluid was decidedly green; (2) 75 per cent alcohol which fixed the slime 
and in two hours had not withdrawn any chlorophyll; (3) 50 per cent alcohol which did not fix and 
was worthless. In the 50 per cent alcohol the bacilli oozed out within 2 hours in quantity and formed 
a milky slime in the bottom of the bottle and all over the ends of the segments. There was not 
much choice between the effect of absolute alcohol and 75 per cent alcohol. 
(168.) Cucumber var. White Wonder. About 20 pricks were made in the center of a leaf-blade 
about 2.5 inches broad. The pricks were all in an area not over 5 mm. in diameter and each side of 
the midrib. The eighth day there was no trace of the disease but the following day (11 a.m.) the 
wilt appeared over an area 5X15 mm. extending from the pricked part outward toward the tip along 
a side vein. The tenth day there was still no wilt except on the pricked leaf. The narrow oblong 
area which appeared wilted the day before had now dried out and much fresh tissue was involved 
in the wilt, about one-sixth of the whole leaf being affected, 7. e., each side of the midrib to the apex 
and also downward over half-way to the base of the blade. The seventeenth day the vine was 
brought into the laboratory and dissected. The leaf-blades were all wilted some days before. With 
the exception of the lowest petiole which was wilted and somewhat yellow at the tip, the petioles were 
all green and turgid. The stem was turgid and normal in external appearance. There was no rot 
at the base of the plant. The interior of the vine was full of bacilli. 
No. 168 was the fourth and last check against the squash and pumpkin inoculations, none of 
which had given any positive results. The internodes of this vine were cut into short lengths and 
put alternately into two bottles. Those in one were covered for 22 hours with 1 per cent tri-nitro- 
phenol dissolved in absolute alcohol; the others were put for the same time into absolute alcohol 
saturated with mercuric chloride. The former proved the best fixative. 
(169.) Tomato (Lycopersicum esculentum). About 20 pricks were made in a green fruit about 
one inch in diameter. Some of the pricks were shallow and some were deep. Many thousands of 
the bacteria were put in. The fourth day the fruit was one-third larger. There was a very narrow 
- rim of dead tissue about the pricks and beyond this a narrow ring of tissue which was darker green 
than natural. This second ring was not over 0.4 mm. broad. On May 9, 24 days after inoculation, 
the tissue around the pricks was slightly sunken. The immediate border, 0.2 mm. in width, was 
dead; beyond this for a short distance (0.5 to 1 mm.) the tissue was a little darker green than natural. 
There were no other signs. The fruit had become three times as big as when pricked and the other 
fruit on the cluster (earlier set) was ripe. On May 14 the inoculated fruit was ripe. The second 
ring referred to above, ripened more slowly than the rest and was still greenish. The fruit was sound, 
normal and well flavored. 
(170.) Tomato. A green fruit about an inch in giclee was pricked 12 times and a great many 
bacteria were inserted. There was no result from the inoculation. The fourth day it resembled the 
preceding. On May 9g the four fruits in the cluster were all growing finely. The pricked one was 
exactly like 169 at this date. On May 20 it was fully ripe and was picked and eaten. It was entirely 
sound. The only result from the pricks was death of ruptured cells and retarded ripening just around 
the track of the needle. 
Remarks.—The following note of June 10, 1895, may be of interest in connection with 
the observations on Nos. 169 and 170. 
Two small green tomato fruits pricked with a pin some weeks ago have become darker 
green around the pricks just as did those previously inoculated with Bacillus trachetphilus. 
Apparently the phenomenon is the reaction of the plant against the puncture and not against 
the bacteria. 
This experiment confirmed the earlier ones. Cucumber and muskmelon were found 
susceptible to the culture used while squash, pumpkin and watermelon were resistant. All 
of the former and none of the latter contracted the disease. 
