WILT OF CUCURBITS. 



229 



the whole leaf-bjade was affected with the exception of about i cm. at the apex of the petiole (fig. 61). 

 Over two-thirds of the blade was dry-wrinkling. The leaf succumbed very quickly. The eighth 

 day after inoculation the pricked leaf-blade was almost wholly dry-wrinkled but the petiole was 

 still turgid. The next noon the nearest leaf each way which showed only the faintest trace of want 

 of turgor at 9 a. m. was flabby and drooping, especially the one below. The petiole of the pricked leaf 

 was still turgid. The tenth day the petiole of the pricked leaf was still green but it was flabby half- 

 way to the base. The shriveled blade was becoming brownish. The first leaf each way was more 

 collapsed than on the preceding day, expecially the lower one. The second leaves each way were 

 still turgid. The eleventh day (10 a. m.) the second leaf below was fully flabby and drooping. The 

 second above then showed only a very slight lack of turgor at the apex of the blade, but at 4 p. m. it 

 was quite flabby and drooped. The twelfth day the petiole of the pricked leaf was green but flabby 

 half-way to the base, the same as on the tenth day. The blades of the first, second and third leaf 

 up were wholly collapsed and also the petioles of the first and second. The same was true of the blades 

 of the first and second leaves down and the upper third of the petiole in the first leaf down. The 

 third leaf below was still turgid. At 5 p. m. the blades of the first and second leaves below and the 

 first, second, and third above were shriveling. The fourteenth day the blade of the pricked leaf was 

 brown-shriveled. The petiole was still green but now flabby nearly to the base and shriveled half- 

 way down. The third leaf down had begun to lose turgor. The petiole of the first and second leaf 

 up were more flabby than that of the pricked leaf. The twenty-ninth day this vine together with 



the other old cucumber-plants, was pulled out 

 to make room for squashes. Dry material was 

 saved for the herbarium. Search was made in it 

 for spores of the bacillus, but none were found. 



(28.) The fourth leaf from the tip was 

 selected for inoculation; the pricks were made 

 near the apex of the leaf and were numerous. 

 The first signs appeared on the morning of Octo- 

 ber 3 1 (5^ days) and first in the pricked area. 

 The pricked portion (the leaf had been purposely 

 inoculated near the apex) was wilted and had 

 become a paler green. Upward the wilting had 

 extended to the apex of the leaf, 1.5 cm. beyond 

 the pricked area, while downward it had extended 

 only 3 mm. beyond the pricked area. The rest 

 of the leaf was sound and turgid. The middle 

 portion of the pricked area (earliest wilt) was 

 brown. At 5 p. m. the wilted area had widened 

 2 mm. or more on each side but had not extended 

 any farther down. The following noon the tip 

 of the leaf had dried out and was hanging down. 

 Both of the apical side lobes were now drooping. 

 The basal lobes and middle basal part were turgid. 

 The eight day the pricked leaf -blade was wholly 

 wilted and two-thirds dry-shriveled. The petiole 



was turgid. Drawings were made of this leaf in the different stages of wilt (see fig. 63). The ninth 

 day (noon) the petiole of the pricked leaf was flabby at the tip and half-way to the stem, i. e., for a 

 distance of 2 inches. No leaves above were drooping. The nearest below was beginning to be 

 flabby. The following noon the petiole of the pricked leaf was still green but flabby nearly to the 

 base. The shriveled blade was becoming brownish especially in the pricked area. No leaves 

 above were wilted and the first leaf below had recovered its turgidity during the night. The eleventh 

 day at 10 a. m. there was no change but at 4 p. m. the first leaf below was flabby. The morning 

 of the twelfth day the petiole of the pricked leaf was flabby to the base and shriveled two-thirds down. 

 No further changes were recorded until the morning of the fourteenth day after inoculation. Then 

 the petiole of the pricked leaf was shriveled to the base and hanging down limp. It was green only 

 in the basal portion. The second leaf up was gone (removed by some one) and the third was flabby. 

 None of the leaves below the pricked one had sound blades but there was a branch 8 inches long some 

 distance below which was green and sound. The petiole of the first leaf below was flabby and 

 shriveled two- thirds of the way to the base. The twenty-ninth day the vine was uprooted 

 and dry material saved from it for the herbarium. Search was also made in it for spores of the 

 organism. 



*FiG. 61. Same as fig. 60, but 20 hours later, the only turgid part of the blade being at the extreme base. 



Fig- 61. 



