WIIvT OF CUCURBITS. 255 



The petiole of the first leaf down was rigid and green. That of the second leaf down was flabby and 

 drooping. It was a smaller petiole. The blades of the first, second, third and fourth leaves up had 

 collapsed. The petiole of the pricked leaf was still normal. The eighteenth day all the leaf-blades 

 had collapsed except the two lowest. The petiole of the pricked leaf was still green and turgid as was 

 the case with all those below it. All the petioles above the pricked leaf were flabby, especially 

 toward their tips. 



(193.) Cucumber. Many pricks were made on the middle apical portion of a leaf-blade 5 inches 

 broad. The leaf was on the ninth node. The 6th day (2 p.m.) the leaf was wilted from the pricked 

 place to the apex. The wilted area widened outward, being about i cm. broad at the pricks and 2 to 

 3 cm. wide farther up. Two days later the bulk of the leaf was still normal but the wilt was spread- 

 ing slowly. May 22, 9 days after inoculation, the whole blade of the pricked leaf had wilted. It was 

 still green and the petiole was turgid. Two days laterthe whole blade of the pricked leaf had shriveled. 

 The petiole was still green and rigid. The twelfth day (10 a.m.) the petiole of the pricked leaf was 

 normal as was also the first leaf up and the first leaf down. Four hours later two-thirds of the blade 

 of the first leaf up had wilted. The fourteenth day the blades of the first and second leaf down were 

 flabby. The petiole of the first leaf down was rigid. The smaller petiole of the second down was 

 flabby and drooping. The blades of the first and second leaf up were wholly flabby and the third up 

 was beginning to show signs of the wilt. The petiole of the pricked leaf was still normal. Four days 

 later the blades of the first three leaves below were dry -shriveled and the petiole of the pricked leaf 

 was flabby at its tip. The petioles of the first and third leaves down were turgid and green. That of 

 the second leaf down was shriveling at its apex. The blades of the first four leaves up were shriveled 

 and the petioles flabby. The blades of the next two above were flabby but the rest of the leaves (half 

 a dozen still farther up) were normal. 



(194.) Cucumber. Many pricks were made in the middle of the blade of a small leaf . The ninth 

 day there were no signs but 2 days later the pricked leaf-blade had a narrow, shriveled, dry strip 

 extending from the pricks to the tip (0.8X3 cm.) showing that the wilt had appeared the preceding 

 day. The twelfth day the whole blade of the pricked leaf had shriveled. The petiole was turgid as 

 were also the leaves above and below. The fourteenth day the first leaf down shriveled. Four days 

 later all the leaves were down and the stem was bowed over in the middle. This was a small vine. 



Remarks. — Three of the cucumbers came down on May 19 (sixth day), and Nos. 

 191 to 194 were very badly diseased before No. 190 showed any constitutional signs. Signs 

 outside of the inoculated leaf did not appear on the latter until after 24 days. From that 

 time on the progress of the disease was as usual. 



May 29, and 30 were very hot. 



On May 21, all of the potatoes were healthy. There was some tearing of the pricked 

 tissues due to rapid growth and on some of the stems there was a superficial blackening 

 of the pricks but no disease resulted. On June 30, all of the potato plants were still free 

 from the disease. 



These numerous inoculations on potato and tomato were made owing to statements 

 by Dr. Halsted (in Bull. 19, Mississippi Agric. Exp. Station, and elsewhere) connecting 

 causally the southern bacterial tomato blight with a bacterial rot of melons observed by 

 him in Mississippi, New Jersey, and elsewhere, and confused at that time, at least in my 

 own mind, with this disease. 



Inoculations of May 25, 1895. 



A series of inoculations was made at 3 p. m., on cucumbers {Cucumis sativus) by spray- 

 ing the striped cucumber- beetle, Diabrotica vittaia, with dilute broth containing Bacillus 

 tracheiphilus and placing them on the plants in an insect cage. The culture used was one 

 in slightly acid potato-broth (tube 3, May 22), containing rolling clouds when shaken. It 

 was examined in a hanging drop and found to contain comparatively few rods, some of 

 which were feebly motile. It was diluted with three times as much distilled water before 

 using for the cage-experiments. 



(195 a to/.) Cucumbers. Six small, old, rather stunted cucumber-vines, from which most of the 

 aphides had been removed, but which would never amount to much without repotting (in 4 pots) 

 were placed in an insect cage. The soil outside and in was thoroughly wet down and a dozen or two 



