276 BACTERIA IN RELATION TO PLANT DISEASES. 



A big loop of the fluid, containing many thousand bacteria (some of which were motile, 

 as determined by examination under the microscope) was put on the clean surface of the 

 leaf, spread a little and then rapidly pricked in, taking special care to make the needle- 

 holes as small as possible. The afternoon was cloudy, rainy, and cooler than the 10 days 

 preceding. On account of the cloudiness and moisture in the air the pricks were not covered 

 over with papers. The plants were examined every day for the first 8 days and frequently 

 after that. Twenty-four plants were inoculated. 



(355-) This plant was 18 inches high and very thrifty. The inoculation was made on the sixth 

 leaf 9 inches away from the stem. The pricked leaf-blade was 5 inches broad. Up to the morning of 

 July 21 there was no trace of the disease but at 3 p.m. of the same day about 0.5 sq. cm. on one side 

 of the pricks was wilted. The following morning there was only a very slight change. By noon of 

 the seventh day the wilt covered about 10 sq. cm., and reached half-way down the blade. The leaf 

 was now cut off close to the stem with a hot knife. Four days later the vine was normal, apparently, 

 except for a droop of the first two blades below and a fainter one of the first two above the node which 

 had borne the pricked leaf. I filled the pot several times with water but an hour later the absorption 

 of the water had not relieved the droop of the foliage. The next day in the afternoon the first two 

 leaves below were cut away. They had not recovered their turgor. Three days later the first leaf up 

 was gone (removed by someone), but the blades of the next four up showed the wilt. The eighteenth 

 day the blades of the second and fourth leaves up were shriveled but the petioles were turgid. The 

 fourth leaf was on the same side of the stem as the second. The blade of the third leaf which was on 

 the opposite side was flabby but had not yet shriveled. The blades of the fifth, sixth, seventh, and 

 eighth leaves up were drooping. The others were turgid The twenty-third day after inoculation 

 all the leaves were shriveled and the stem itself was beginning to shrivel. The vine was about 

 5 feet long, i. e., it trebled in length after being inoculated. It was staked up. 



(356.) This was a thrifty plant about 28 inches high. The sixth leaf was pricked 10 inches from 

 the stem. The pricked leaf-blade was 6 inches broad. The sixth day no signs had appeared but at 

 noon of the following day there was a slight wilt in the pricked area and 2 days later this wilt covered 

 about 5 sq. cm. The eleventh day (9 a.m., July 27) the pricked part had dried out and the wilt had 

 increased only slightly (i to 2 sq. cm.). At 3'' 30' p.m., however, the wilt covered an area of about 

 10 sq. cm. The leaf was now cut off near the stem with a hot knife. Twelve days later no further 

 signs had appeared, but the seventeenth day after the removal of the pricked leaf (28 days after 

 inoculation), the blade of the first leaf below and of the first and second up were flabby. Examined 

 microscopically the petioles of these three leaves were found to contain bacteria. 



(357-) This plant was 19 inches high. The inoculation was made 8.75 inches from the stem. 

 The pricked leaf-blade was 5 inches broad. The fifth day, at 10 a.m.,there had been no change in 

 the appearance of the pricked leaf, but at i p.m., there was a slight wilt. At 3 p. m. I removed the 

 leaf at the base with a hot knife, about 2 sq. cm. in and around the pricked area, having wilted 

 distinctly. None of the other leaves ever showed any trace of the wilt. On September 23 (69 days) 

 the plant was still living and free from the disease. 



(358.) This vine was 20 inches high and thrifty. The sixth leaf-blade was 5 inches broad. It 

 was inoculated 7.5 inches from the stem. The sixth day the pricked leaf still presented a normal 

 appearance, but the following day at noon there were about 3 sq. cm. of wilt in and around the pricked 

 portion. Two days later (hot again) the wilted area had increased to 5 or 6 sq. cm. The tenth day 

 there was a bad wilt of the pricked blade, mostly without change of color, but which I could not 

 overcome by copious watering. The next morning the leaf-blade had changed color throughout (the 

 characteristic dull green) and the outer three-fourths of the petiole was flabby. I did not remove this 

 leaf. The twenty-third day the blade of the first leaf down and those of the first three leaves up had 

 wilted. The petioles were turgid. 



(359-) This plant was 17 inches high and thrifty. The fifth leaf-blade which was 6.5 inches 

 broad, was inoculated 8 inches from the stem. The fifth day, at 10 a.m. no signs had appeared but 

 at i p.m. there was slight wilt in and around the pricked area. At 3 p.m. I removed the leaf with a 

 hot knife, cutting the petiole close to the stem. About 3 sq. cm. of the leaf had wilted in the pricked 

 area, and immediately around it. The eighteenth day (13 days after the removal of the pricked leaf), 

 the foliage drooped a little, but it was doubtful whether this was due to the disease. The day was 

 hot, still and cloudy. I watered the pot which had become rather dry, but this did not cause the 

 leaves to recover their turgidity. Five days later (August 8) the blades of three additional leaves 

 were wilted. 



(360.) This plant was 19.5 inches high. The fifth leaf was inoculated 9.5 inches from the stem. 

 The pricked leaf-blade was 5 inches broad. The eighth day there was no trace of the wilt but the 



