246 BACTERIA IN RELATION TO PLANT DISEASES. 



The petiole was still turgid and none of the other leaves were affected. Twenty-four hours later the 

 tip of the petiole of the pricked leaf had begun to shrivel. The blade of the first leaf down had 

 shriveled but the first leaf above showed no sign of the wilt in spite of the fact that the first internode 

 below was three times as long as the first one above. The tenth day the first leaf up had collapsed. 



(1096.) Muskmelon. A small vine in the same pot as the preceding was pricked on the blade 

 of one leaf. 



The morning of the fifth day one-eighth of the inoculated leaf (the apical pricked portion) had 

 become dull-green and wilted. Twenty-four hours later the whole of the blade of the pricked leaf 

 had collapsed. Two days later the pricked blade was dry shriveling. The petiole was still turgid 

 and none of the other leaves showed any trace of the wilt. The following day half of the petiole of the 

 pricked leaf had shriveled and the blade of the first leaf up had collapsed. The next day (afternoon) 

 the upper part of the stem had wilted. The vine was'cut and put into alcohol for study of location 

 of bacilli by means of paraffin sections. They were found abundant in the vessels of the stem on 

 microscopic examination. 



(109c.) A small melon in the same pot as loga and 109J was held as a check. It remained 

 healthy. 



(i loa.) Muskmelon. A small vine was pricked on the blade of one leaf. 



The fifth day seven-eighths of the pricked blade had wilted. Twenty-four hours later the whole 

 of the leaf-blade had collapsed. Two days later the pricked blade was dry-shriveling, the petiole 

 turgid. The blade of the first leaf down, which had begun to show signs of wilting the previous after- 

 noon, had collapsed. The first leaf up was still normal. Twenty-four hours later the petiole of the 

 pricked blade was flabby half-way down. The blade of the first leaf down had shriveled and that 

 of the first one up showed very slight signs of loss of turgor. The first internode above was not half 

 as long as the first one below. The next day the upper part of the stem was wilted and the vine was 

 cut, brought into the laboratory and put into alcohol for sections: These when examined under the 

 microscope showed the presence in the vessels of numerous bacteria. 



(i 106.) Muskmelon. The blade of the first true leaf of a small vine was pricked and inoculated. 



The fifth day about one-fifteenth of the pricked leaf-blade had wilted in a small spot on one 

 side near the apex and within the pricked area. Twenty-four hours later about three-fourths of the 

 leaf-blade hung flabby. Two days later the pricked blade had begun to dry-shrivel. One cotyledon 

 and the next leaf above the pricked one had begun to wilt. The following morning the petiole of the 

 pricked leaf had begun to wilt at the apex. The blade of the first leaf up had wholly collapsed. 

 January 13 the upper part of the stem was wilted and the vine was cut and put into alcohol. Sec- 

 tions examined under the microscope showed the presence of bacteria in the bundles of the stem. 



(hoc.) a vine growing in the same pot as iioa and b was held as a check and remained free 

 from the wilt. 



(ma.) Muskmelon. The blade of one of the leaves of a small vine was pricked and inoculated. 



The fifth day over one-half of the pricked leaf blade (apical pricked part) had wilted. By the 

 following morning the whole leaf had collapsed. Two days later the first leaf above the pricked one 

 had begun to wilt. (Since 3 p.m. the preceding day). The morning of the ninth day the first leaf 

 above had shriveled and the wilt had invaded the petiole of the pricked leaf. The plant was now 

 removed and examined microscopically. The vessels were found to contain bacilli a part of which 

 were motile. 



(i iih.) Muskmelon. A vine growing in the potwith ma was pricked on one of its leaf-blades. 

 The eight day there was no trace of the wilt, but 24 hours later about one-fourth of the apex and 

 one side of the pricked blade had wilted and changed to a dull green. The wilt began in the pricked 

 area. The time from the insertion of the bacteria to the appearance of the wilt was about Sf days, 

 i. e., wilt appeared on the ninth day. The tenth day the stem was still turgid. Vine iiib was the 

 last of the eight melons to show the disease. A microscopic examination was made and bacteria 

 were demonstrated in the bundles of the stem. 



(inc.) A vine growing in the pot with ma and b was held as a check and remained free from 

 the wilt. 



(112.) Japanese Pear (Pyrus sp.). A small green shoot, 2 inches long, and a half-grown leaf of a 

 Japanese pear seedling were pricked carefully. 



The ninth day there was no trace of the disease, nor did any signs appear later on. 



(113.) Cucumber (Cucumis sativus). An old cucumber vine growing in one of the insect cages 

 (No. 38) in which infection had failed was pricked in the apical portion of one leaf-blade. The after- 

 noon of the seventh day there were no signs of the wilt, but at 10 a.m. of the following day about one- 

 sixth of the blade had wilted in the pricked area (fig. 66). The lowest sign of wilt was 1.5 cm. from 

 the base of the blade, and the petiole was 5.5 cm. long. Thus there were 7 cm. of healthy looking 

 tissue separating the diseased part from the stem. The leaf was now cut away close to the stem to 



