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268 BACTERIA IN RELATION TO PLANT DISEASES. 
INOCULATIONS OF FEBRUARY 26, 1896. 
A set of inoculations was made in the hothouse at 2 p. m., from a white, wet-shining, 
sticky culture of Bacillus tracheiphilus on steamed carrot (tube 2 February 18, from 1, 
February 13 which was a potato culture made from a fermentation-tube (No. 1, January 20) 
containing cane-sugar. The plants inoculated were: Benincasa cerifera, Cucurbita foeti- 
dissima, Cucurbita californica, cucumber, muskmelon, watermelon and Datura stramonium. 
Numerous bacteria were put in with each inoculation, which was made with a sharp- 
pointed steel needle. All of the plants were examined on February 28 and February 29, 
and were free from disease. 
(272.) Benincasa cerifera. This was a small plant having three leaves besides the green coty- 
ledons. Many pricks were made on the middle leaf. The plant appeared healthy on March 5. The 
first signs were noted on March 6 at 2 p. m. (end of the eighth day) at which time there was a slight 
wilt extending outward from the pricks to the margin. ene following day fully half of the pricked 
leaf had wilted. ‘Two days later the whole of the blade of the pricked leaf had wilted, as also that 
of the first leaf above and below. The sixteenth day the leaves were badly shriveled, but the stem 
was normal. Material was saved in alcohol. On microscopic examination enormous numbers of 
bacteria were found in the vessels (slide No. 202). 
(273.) Cucurbita foetidissima. ‘This vine was grown from seed planted October 11, and at 
the time of inoculation had eight good leaves. Many pricks were made on the under side of an 
upper leaf. The fifth day (9 a. m.) the leaf looked suspicious and at 1"20™ p.m. there was distinct 
wilt at the tip and a dull green color where pricked. The following day there was little change. The 
next day the pricked area had changed to a whitish green and the terminal one-fifth of the blade 
hung flaccid. The following day about one-third of the leaf was wilted and 28 hours later (close of 
eighth day) there was a bad collapse of two-thirds of the pricked blade. The beginning of the eleventh 
day the whole of the blade of the pricked leaf had wilted but the petiole was still rigid. The blades 
of the first and second leaf up were now inclined to droop. Two days later the blade of the first leaf 
down waswilted. Allthe petioles were still rigid. The sixteenth day all the leaf blades had shriveled. 
The stem and petioles (lower two-thirds) were normal. The plant was put into alcohol. On micro- 
scopic examination the bundles of the petiole of the inoculated leaf (fig. 77) were found filled with 
bacteria and badly disorganized (slide No. 254). The bacteria also extended into the bundles of the 
fleshy root but here the disorganization was less. 
(274.) Cucumber (Cucumis sativus). This was a thrifty young plant. Many pricks were made 
on the tip of an upper leaf. The fifth day (9 a. m.) there was wilt and change of color in an area of 
10X3 mm., along one side of the pricked area which was about 10X10 mm, in diameter. At 1° 
p.m. of the same day the wilted area was twelve times as large. The following morning there was 
little change, but 24 hours later the terminal eighth of the leaf was drooping. The next day the 
change of color in the wilted area was more decided but the latter had not increased much. At the 
end of the ninth day there was very striking wilt confined to the terminal half of the pricked leaf, 
a wedge-shaped area 7.5 cm. long by 2.5 cm. wide (in the widest portion). It was dull green and the 
tip was drooping. ‘Twenty-five hours later the whole of the blade of the pricked leaf had wilted. 
The rest of the vine was normal. On March 9, the blades of the first two leaves above and the first 
two below had wilted but the petiole of the pricked leaf was still rigid. Five days later (seventeenth “ 
day) the vine was badly wilted and was pulled up for microscopic examination. ‘The stem was green 
and turgid but its vessels contained a sticky bacterial slime which strung out in long, delicate threads. 
The middle part of the stem was saved in alcohol. 
(275.) Cucumber. This was an old plant. Many pricks were made on the blade of an old, 
upper, whitish leaf. On March 3, at 10a. m., there were no signs but 24 hours later half of the leaf 
was flabby and drooping, on the pricked side. It was now nearly 7 days since the leaf was pricked. 
The following day the whole of the pricked blade was dry shriveled and the tip of the petiole was 
slightly flabby. On March 6 (end of ninth day) the petiolehad shriveled. ‘The rest of the vine was 
normal. ‘The following day there were constitutional signs. By 1o a.m. of March 9 everything 
had collapsed except the green stem and a few small basal leaves. 
(276.) Cucumis melo var. dudaim. ‘This was a small plant. Many pricks were made on one 
leaf-blade. The fifth day thete was slight wilt in the pricked portion and running out to one margin 
of the blade. The following day there was little change, but 24 hours later the whole pricked leaf 
was drooping. ‘This, however, was favored by a dry soil because, on watering, the leaf recovered its 
turgor in the afternoon with the exception of the tissue immediately around the pricks. The next 
morning the pricked leaf was turgid with the exception of a wedge-shaped piece extending from the - 
