270 BACTERIA IN RELATION TO PLANT DISEASES. 



Remarks. Datura stramonium resisted. Local signs were obtained on the watermelon 

 but there was no general infection of the plant. Local and then constitutional signs appeared 

 on the cucumbers, on Cucurbita foetidissima, C. calif arnica, Benincasa cerifera and on the 

 little melon, Cucumis melo var. dudaim. The old and young cucumber proved equally 

 subject to this desease. 



The bitter plant which I have called Cucurbita calif ornica was grown from seeds sent 

 to Mr. Gilbert Hicks by Prof. J. W. Tourney of Arizona. It came to me unnamed and I 

 had much difficulty in classifying it. The plant was finally determined for me by Dr. J. N. 

 Rose of the U. S. National Herbarium. 



INOCULATIONS OF APRIL 4, 1896. 



Four vines of Melothria scabra, three of cucumber, one of Echinocystis lobata, one of 

 watermelon and two of Cucumis erinaceus were inoculated with a pure culture of Bacillus 

 tracheiphilus taken from tube i , March 30. A big loopful of the bacterial slime was put on 

 one leaf of each plant and pricked in with numerous fine punctures, using a small sharp 

 steel needle. In some cases an additional loop of the slime was afterwards put on over the 

 pricks which were protected from direct sunshine. The rods in this tube were mostly in a 

 state of active motility as determined by examination in a hanging drop. Inoculations 

 in each case were made on the blade of the leaf and were very thorough. 



(282.) Melothria scabra (from Mexico). Up to April 13 there were no signs. The eleventh day 

 there was a yellowing of the tissue about the pricks, but no wilt of the blade. Two days later there 

 was little change (the weather for the past six days had been very hot). The twenty -fourth day 

 the pricked leaf had shriveled but the rest of the plant was normal. On June 16 the plant was 

 still alive the inoculation having failed to kill it. On June 25 (82 days) there was still no result 

 other than the local injury. 



(283.) Melothria scabra. There were no signs until the eleventh day. At that time a very little 

 of the tissue in the pricked area was dead (i to 2 sq. mm.) but there was no general wilt of the leaf. 

 Two days later the pricked leaf was yellower but not wilted. The twenty-fourth day the pricked 

 leaf had shriveled but none of the others showed any trace of the wilt. On June 16 the plant was 

 still living. The inoculations failed to induce constitutional signs. 



(284.) Melothria scabra. On April 13 the plant was normal. The eleventh day the leaf -blade 

 was yellowish green and puffed out where pricked. Two days later the pricked leaf was yellow 

 around the pricks but not wilted. The twenty-fourth day the pricked leaf which had shown itself 

 very resistant at first, had shriveled. The other leaves were normal. June 16 the plant was still 

 living and did not show any constitutional signs. 



(285.) Melothria scabra. This plant behaved like the preceding. The inoculation did not harm 

 the plant beyond the pricked leaf. 



(286.) Common Cucumber. No record earlier than April 13. On that day there was wilt on 

 one side of the leaf around the pricks. Two days later the whole blade of the pricked leaf was droop- 

 ing. The thirteenth day the whole of the pricked leaf-blade had wilted, also two leaves above and 

 one leaf below. The petioles were turgid. The twenty-fourth day the plant was dead. 



(287.) Common Cucumber. No record earlier than April 13. On that day there were no signs 

 of the disease, but 2 days later there were a few square centimeters of wilted tissue in and around 

 the pricks. The thirteenth day the whole of the pricked blade was wilted. The leaves above and 

 below were normal. The twenty-fourth day the stem was still green, but the leaves had wilted. 



(288.) Common Cucumber. The ninth day the pricked leaf was normal, but 2 days later there 

 was wilt of a few square centimeters in and around the pricked area. The thirteenth day the whole 

 of the pricked leaf had wilted. The leaves above and below were normal. The twenty-fourth day 

 the plant was dead. 



(289.) Echinocystis lobata. No record earlier than April 13. The afternoon of that day there 

 was wilt of the tip of the leaf, i. e., of the tissue in and around the pricked area. There was only a 

 slight change the following noon. The eleventh day most of the pricked leaf was turgid. The wilted 

 portion had dried out and apparently the disease had come to a stop. Two days later there was no 

 increase of the wilt and the greater part of the pricked leaf was normal. The twenty-fourth day the 

 plant was growing rapidly and had recovered. On June 16 the plant was still living. It had made 

 a long growth and blossomed. Only a small part of the pricked leaf succumbed. 



