258 BACTERIA IN RELATION TO PLANT DISEASES. 



ledon had begun to shrivel. The first leaf up showed a trace of flabbyness. The next afternoon the 

 other cotyledon was drooping. The other leaves showed no sign of the wilt. Two days later the vine 

 was bowed over at the root and all the foliage had wilted. When the stem was cut a stringy bacterial 

 slime oozed out. The vessels were gorged with a schizomycete which had flooded out into the paren- 

 chyma. Some of the rods were distinctly larger (longer and broader) than the rest. The motility 

 was not made out satisfactorily. Cultures were started from the interior of this vine and a section 

 was saved in alcohol for study. (The cultures made were No. 9, a streak on agar, stock 82c, and 

 Nos. 10 to 14 on potato-cylinders.) The agar culture failed. With possibly one exception (tube 11), 

 the inoculated tubes of potato developed pure cultures of B. tracheiphihis. At the end of 5 days 

 the surface of the potato was covered by a very thin, exceedingly sticky layer, so exactly the color 

 of the potato that it was to be distinguished from it only by its wet-shining appearance. In tube 1 1 

 most of the culture was of this character, but in the center there was a raised, slightly yellowish 

 portion, believed to be a contamination. 



(211.) Gherkin. By the ninth day the entire blade of the pricked leaf had wilted and changed 

 color. The petiole was rigid. The blade of the first leaf up was wilted and the edges were rolled 

 inward. The second leaf up was still green and turgid. Twenty-four hours later the cotyledons were 

 hanging down and the second leaf above the pricked one was drooping. The following day there was 

 little change, but 24 hours later the blades of all the leaves (it was a small plant) were badly wilted. 

 The petioles were still rigid. Four days later the leaves had shriveled and also the base of the stem. 

 The plant was brought in and dissected. Under the microscope, the vessels were found to be gorged 

 with a sticky bacillus which strung out when touched. The tissues around the vessels were disorgan- 

 ized. The bacillus was motile and some of the rods were much larger than 

 others longer and especially broader. 



(212 a and b.) Gherkin. There were two vines in the same pot. ( )ne 

 contracted the wilt and was removed on the seventh day when half of the 

 pricked leaflet was wilted (2 p. m.). At that time the second vine was healthy 

 but 2 days later (3 p. m.) it had two wilted leaves, the pricked one and the 

 next one above it. 



(213 and 214.) Gherkins. These damped off . 



(215.) Winter Squash var. Pikes Peak. Two leaves were inoculated. 

 The ninth day one of the pricked leaves had wilted outward from one of 

 the groups of pricks and this area had changed to a light dull green. There 

 were about twenty pricks in this group and the wilt did not include all of 

 Fig- 71.* them (fig. 71). During the next three days there was little if any change. 



The sixteenth day about one-third of the pricked blade showed wilt and was 

 drooping. There was also a small wilt-spot on the other leaf, including and surrounding the group 

 of pricks. A week later the greater part of the blade of the lowest pricked leaf was flabby and yellow. 

 The other inoculated leaf was dead in the pricked area, yellow around the pricks and slightly flabby 

 on the whole of that side. November 1 1 (37 days after inoculation) the lowest leaf was dead and 

 brown-shriveled down to the stem. The blade of the upper pricked leaf was shriveled and the petiole 

 flabby at the apex and yellow its whole length. The blades of the next two leaves above were 

 beginning to be a paler green. December 3 the vine was 13 inches long and had twelve leaves, 

 those which had grown since the inoculation being dwarfish and not bright green. The next leaf 

 up as well as the stem was very yellow. The plant was blossoming freely. December 10 the plant 

 was still alive but stunted and yellowish (see photograph, fig. 53, made of this vine and a check). 

 Thin sections were made of the stem and examined microscopically, the bacteria being detected in 

 the bundles. Very few vessels were found to contain many bacteria. There was only one densely 

 plugged vessel, and that was on the outer margin of the xylem near the cambium. The tissue was 

 broken down on the outer margin of the xylem in several bundles. The cross-sections were not 

 sticky. Stem, saved in alcohol. Sections cut from this stem show numerous bacteria in one or 

 more vessels of five bundles but most of the vessels are free from them. 



(216.) Winter Squash var. Pikes Peak. The ninth day after inoculation about 1 sq. cm. of the 

 blade changed color and wilted, beginning in one of the three groups of pricks (fig. 72). The leaf was 

 also slightly yellow around the other two groups of pricks. Twenty-four hours later the V-shaped 

 small marginal piece of sound tissue was wilted, but otherwise there was little change. The sixteenth 

 day about one-fourth of the pricked leaf was yellowish green and drooped slightly. Seven days later 

 the portion above the line of October 2 1 (see drawing) was yellow and slightly flabby. The rest of the 

 leaf was normal and there were no constitutional signs. November 1 1 (thirty-seven days after inocu- 



M'ig. 71. Leaf of winter squash (plant No. 215) inoculated with B. tracheiphihis, Oct. 5, 189.5. On Oct. 14 the 

 shaded area was freshly wilted. Up to Oct. 17 there was little change, but on Oct. 21 about one-third of the leaf- 

 blade was wilted and drooping. For further changes in this plant see fig. 53 A . 



