278 BACTERIA IN RELATION TO PLANT DISEASES. 



of the blade. The leaf was now cut away close to the stem with a hot knife. There were no signs 

 until after August 5. On August 8 (eight days after the removal of the pricked leaf) the blade of the 

 first leaf up hung flabby and the one below had wholly shriveled. The next three up showed a slight 

 droop. Five days later several more leaves were drooping. 



(368.) This plant was 20.5 inches high. The sixth leaf was inoculated, 6.5 inches from the 

 stem. Its blade was 5.5 inches broad. At 9 a.m. of the fourth day there were no signs, but at 2 

 p.m. there was a wilted area extending from the pricked part toward the tip of the leaf, affecting 

 about 2 sq.cm. At 5 p.m. the wilt was decided, involving all of the pricked area and a narrow strip 

 extending nearly to the apex of the leaf (about 2 cm.) . The pricked leaf was now cut away at the base. 

 This plant was examined July 27 and 31, August 8, 13, 17, 19, 28, and at later dates. None of the 

 other leaves became affected. On September 23 the plant was still living and free from this disease. 



(369.) This plant was 16 inches high. The fifth leaf was pricked 9 inches from the stem. The 

 pricked leaf-blade was 6 inches broad. The fifth day at 10 a.m. the leaf was still normal in appear- 

 ance but 3 hours later there was a slight wilt in and around the pricked area. By 3 p.m. the wilt had 

 spread rapidly. It then covered about 8 or 9 sq. cm. and reached nearly half-way down the blade. 

 I now removed the leaf at the base using a hot knife. (This leaf was saved in alcohol for sections.) 

 There were no signs until after July 27. Ten days after the removal of the pricked leaf (July 31) the 

 blades of the first two leaves above were drooping badly. The first leaf below was normal. Five days 

 later several more leaves above the pricked one were wilted. The eighteenth day after the removal 

 of the pricked leaf additional leaves near the top of the vine were wilting. 



(370.) This plant was 19 inches high. The fifth leaf was inoculated 7.75 inches from the stem. 

 The pricked leaf-blade was 6 inches broad. The fifth day, at 10 a.m. there were no signs but at 3 p.m. 

 there was wilt of about 0.5 sq. cm., in the center of the pricked area. The wilt increased very little 

 over night but the seventh day at noon it covered about 5 sq. cm. around the pricks. The eighth day 

 was cool with heavy rains in the afternoon and the wilt was at a standstill. The following day, 

 however, was sunny, transpiration was greater, and the wilt of the pricked leaf, at 2 p.m. covered 

 about 1 2 sq. cm. and reached nearly half-way to the base of the blade. I now cut the leaf away at 

 the stem with a hot knife. None of the other leaves contracted the disease. 



(371.) This plant was 20 inches high. The fifth leaf was inoculated 9.5 inches from the stem. 

 The pricked leaf-blade was 5.5 inches broad. There were no signs up to noon of July 23. The ninth 

 day (July 25, 2 p.m.) there was wilt of about 3 sq. cm. in and around the pricks. Two days later 

 (10 a.m.) the pricked area was dead but there had been only a slight increase of wilt. The following 

 afternoon (July 28, 5 p.m.) the leaf was cut away close to the stem with a hot knife. At that time 

 there were about 8 sq. cm. of wilted tissue in the vicinity of the pricks. There were no constitutional 

 signs until after July 3 1 . On August 8 ( 1 1 days after the removal of the pricked leaf) the first leaf below 

 was shriveled and the blades of the second below and first above drooped a little. The sixteenth day 

 after the removal of the pricked leaf there was bad wilt of several additional leaves above the inocu- 

 lated one. I now cut off three leaves and examined them. On touching the cut ends with my finger 

 the bacteria in the vessels strung out i to 2 cm. in numerous fine, sticky, cobwebby threads. 



(372.) This plant was 22 inches high. The fifth leaf was inoculated 9.5 inches from the stem. 

 The pricked leaf-blade was 6 inches broad. Up to the fifth day at 3 p.m. no signs had appeared, but 

 the morning of the sixth day about i sq. cm. of tissue in the pricked area was wilted. By noon of the 

 following day the wilted area was about fifteen times as large and reached half-way to the base of the 

 blade. The leaf was now cut off at its junction with the stem, using a hot knife. None of the other 

 leaves contracted the disease. On September 23 (69 days) the plant was still living and free from 

 the disease. 



(373-) This plant was 23 inches high and very thrifty. The sixth leaf was selected for inoculation. 

 Its blade was 5 inches broad, and the pricks were made 8 inches from the stem. On the seventh day 

 at noon there was about i sq. cm. of wilt in the outer part of the pricked area. During the next 2 

 days the wilted area increased not more than i sq. cm. The eleventh day, at 10 a.m., the pricked 

 area was dead and the surrounding tissue yellow, but there was only a slight increase of the wilt. 

 Four days later (July 31, 2 p.m.) there were about 25 sq. cm. of wilt, reaching three-fourths of the way 

 to the base of the blade. With a hot knife the leaf was now cut away at its junction with the stem. 

 There were no constitutional signs until after August 5. Eight days after the removal of this leaf 

 the blade of the first leaf up was drooping decidedly and the blades of the next two above showed 

 a faint wilt (August 8, 10 a.m.). I now cut away the petiole of the first leaf up at its base, using a 

 hot knife and examined it by touching the cut end with my finger. The surface ooze was sticky and 

 strung a little. During the next 5 days several additional leaves wilted. 



(374.) This plant was 22 inches high. It was inoculated on the fifth leaf 10.5 inches from the 

 stem. The pricked leaf-blade was 6 inches broad. Up to the fifth day at 10 a.m. there were no 

 signs, but 3 hours later there was a slight wilt, and at 3 p.m. there was a decided wilt involving about 



