2 1,2 BACTERIA IN RELATION TO PLANT DISEASES. 



quently potato-culture No. 3, November 12, from one of these potato broths, yielded a thin, smooth, 

 gray-white, growth, almost exactly the color of the surface of the steamed potato, but easily dis- 

 tinguished from it by its wet-shining appearance. This bacterial slime was viscid, stringing up 2 to 

 6 em. when its surface was touched with a needle. Once I pulled the needle entirely out of the test 

 tube before the gummy thread broke, and once from a cover-glass I stretched it up 20 cm. Examined 

 in a hanging drop some of the rods were quiet, while others of the same form were actively motile. 

 In other words, this potato-culture was an exact duplicate of No. 8, October 17, from which the broth 

 was inoculated which served to infect this vine. The organism stained readily in carbol-fuchsin 

 ( 1 to 3 min. exposure). The remaining part of the vine was left in the hothouse till the twenty-ninth 

 day but no further developments were recorded. Dry material was saved for the herbarium. A 

 futile search was made in it for spores of the bacillus. 



(30.) The sixth leaf from the tip was pricked many times in one of the side lobes. There was no 

 result. The pricked leaf remained thrifty although, by actual count, it had received forty pricks in 

 one lobe. The plant was under observation until November 8(14 days) and probably until Novem- 

 ber 23. 



(31.) The twelfth leaf from the tip was pricked many times in the basal portion of the blade to 

 one side of the center. By 10 a.m. October 31 the whole leaf had collapsed, changed color and was 

 flaccid. It had already begun to dry out on the pricked side showing that the infection had come from 

 that portion of the leaf. These were the first signs noted. The rest of the foliage was sound. The 

 following day at noon the drooping leaf-blade was dry-shriveled except one basal lobe which was 

 still flabby. The petiole was turgid. The next afternoon the blade of the pricked leaf was wholly 

 dry-shriveled and the upper part of the petiole was flabby. The leaves to either side were turgid. 

 The tenth day (noon) the petiole of the pricked leaf was still green, but flabby nearly to the base. 

 It was not yet shriveling. The shriveled blade was becoming brownish. The rest of the foliage was 

 still normal. There was no visible change until the twelfth morning. Then the petiole of the pricked 

 leaf was flabby throughout and shriveled nearly to the base, but green. The leaves to each side, 

 which were separated from the pricked one by long internodes, were still turgid. At 5 p.m. the first 

 leaf below was flabby and drooping on one side (basal and middle lobes). The morning of the 

 fourteenth day the blade of the pricked leaf was greenish brown (like No. 28). The petiole, shriveled 

 nearly to the base, was still green but of a dull shade at the tip. The entire blade of the first leaf down 

 had collapsed and had begun to shrivel at the edges. All the leaves above (7 in number) had collapsed 

 and hung on limp petioles. They were still green. The twenty-ninth day the plant was pulled up 

 and a part of it saved dry for the herbarium. 



(32.) The eleventh leaf from the tip, i.e., one well down on the old stem was pricked many times 

 in the center of the blade. In a few days the leaves began to turn brown at the edges and by the 

 sixth day the pricked leaf had browned and was almost entirely dried out but not from this disease. 

 The plant had exhausted the soil in the 4-inch pot and done its life-work. Like many others of this 

 planting it had probably ripened a small fruit. This vine was left to grow as long as the others but 

 there was no result. The bacteria never reached the stem but were isolated from their necessary 

 water-supply and destroyed in the browning leaf. 



(23-) Many deep punctures were made in a small green fruit. The sixth day there were no 

 signs of the wilt. The little cucumber was still green, for the most part, but there was a slight yellow- 

 ing on one side, due probably to ripeness. It was still turgid and healthy. The foliage was normal. 

 The tenth day after inoculation the little pricked cucumber looked as healthy as ever save for a 

 water-soaked appearance around some of the pricks. There was no suspicion of rot and the 

 water-soaked appearance might have been due to handling rather than to the bacteria as I saw simi- 

 lar appearances the preceding winter in Anacostia hot-houses on unpricked as well as pricked fruits. 

 The blade of the small leaf from the axil of which the pricked fruit arose was normal the night before 

 but was at this time flabby. Its petiole was turgid and also the leaves above and below. The next morn- 

 ing there was no change but at 4 p.m. the little leaf subtending the fruit had wholly collapsed and was 

 shriveling. The first, second, third, and fourth leaves above the inoculated one were now flabby. 

 Those below were turgid. The vine had bent or trailed so that the former were below the fruit. The 

 morning of the twelfth day there was no rot in the fruit but it was less turgid and yielded more under 

 slight pressure than on the preceding day. The first and second leaves below (up in relation to the 

 earth ) were still turgid. The fourteenth day the tip of the vine was shriveling. A little white fungus 

 which had undoubtedly gained entrance through one of the needle-pricks, now caused a small sunken 

 place. The tuft of white hyphae was first noticeable the preceding day. The leaves below were not 

 yet flabby except the one subtending the pricked fruit. The leaves above were shriveled. The upper 

 part of the vine was now bri lUght into the laboratory for microscopic examination. The vessels were 

 found to he full of the bacillus which strung out in fine gummy threads from the cut surface of the 

 stem and of the inoculated fruit. The bacillus was especially abundant in the latter. The inner 



