262 BACTERIA IN RELATION TO PLANT DISEASES. 



at first as to the nature of the organism in the bundles of this fruit because I had not hitherto 

 known of the occurrence of the cucumber-wilt in hothouses, except as the result of my 

 inoculations. It proved, however, to be infectious and yielded a long series of cultures and 

 successful inoculations. 



This experiment also shows that the squash is much more resistant than muskmelon 

 or cucumber, at least to what I have come to call the cucumber strain. 



Inoculations op November 29, 1895. 



A muskmelon and a cucumber-vine were inoculated with Bacillus tracheiphilus from 

 potato (?) tube 2, October 26 (from agar-stab of May 7). In each case many pricks were 

 made on one leaf-blade. 



(224.) Muskmelon (Cucumis melo). The eleventh day the pricked leaf-blade was partially 

 wilted but the same was also true of two below and the cause was doubtful. Perhaps the wilt was due 

 to the sulfuring done in the house some days before as other vines showed similar results. The seven- 

 teenth day it was still doubtful as to what was the cause of the wilt. December 3 1 the leaves were 

 spotted and brown but it was doubtful if the bacteria were alive. January 7 the vine had shriveled 

 down to the long hypocotyl which was still normal. It was now cut and examined in two places for 

 bacteria but none were found. 



(225.) Cucumber {Cucumis salivus). March 4 this vine showed no result from the inoculation. 



Remarks. — The culture used was 34 days old, and probably dead. 



Inoculations of December 3, 1895. 



Bacilli were squeezed out of the cut stem of a wilted muskmelon-vine (No. 221) and 

 direct inoculations were made, at 3 p.m., into the following cucurbitaceous plants : common 

 gourd {Lagenaria vulgaris); Balsam apple {Momordica balsamina); Gherkin (Cucumis 

 anguria); vegetable sponge {Luff a acutangula) ; and wild gourd {Cucurbita foetidissima) , a 

 big rooted species native west of the Mississippi River. All of these were small plants, i. e., 

 only 3 to 8 inches high, but not stunted except the Luff a which was an older vine growing 

 slowly and blossoming. The inoculations were made by means of groups of needle-pricks 

 on the blade of one leaf. The bacteria used were sticky. Four days later these plants, 

 all of which were growing nicely, were re-inoculated, each on another leaf-blade, using 

 sticky bacterial slime out of the vessels of cucumber- vine No. 222. Great quantities of 

 the bacteria were used. All of the leaf -blades of vine No. 222, from which these inoculations 

 were made, had wilted and the interior of the stem was gorged with the bacteria. The 

 vines were re-inoculated to make infection doubly certain. A limited area of the surface 

 was first thoroughly wetted with the sticky slime and then many needle-pricks were made 

 into this area. The inoculations were made in the hothouse. 



(226.) Common Gourd. Twenty-eight days after inoculation (December 31), the plant had 

 grown much and was blossoming freely, having shown no signs of the wilt. Three months after inocu- 

 lation there was no general wilt. 



(227.) Common Gourd. The eighth day at i p.m., the pricked leaf had changed color in the 

 terminal part of the blade and two-thirds of this blade hung limp (it was normal at 10 a.m.). The 

 period of incubation was a few hours less than 8' days. Five days later the blade of the pricked leaf 

 had wholly collapsed and part of it was yellowish. The next leaf below (the one which was re-inocu- 

 lated December 7), was still normal. About 3 weeks after inoculation the wilted leaf had shriveled 

 to the stem but none of the others showed any indications of wilt although the first internode up was 

 only half an inch long and that next below was only 0.75 inch. January 10 (38 days after inoculation) 

 the next four leaves above the pricked one and also one below had collapsed. Previous to this there 

 had been no indication of the disease (except wilt of these four leaves for a few hours only on December 

 16, ascribed to lack of water), and I thought the plant had overcome the bacteria. Careful examina- 

 tion of the stem in two places, i. e., just above and below the pricked leaf, showed no bacteria and the 

 wilt was not accounted for. 



(228.) Common Gourd. The plant grew and blossomed freely. The inoculation produced no 

 disease. 



