252 



BACTERIA IN REIvATlON TO PLANT DISEASES. 



Many- 



Many 



(156.) Pumpkin var. Nantucket Sugar (Cucurbita sp.). Many pricks were made on various 

 parts of a leaf-blade about 2.75 inches broad. 

 There was no result from the inoculation. 



(157.) Pumpkin var. Nantucket Sugar. This vine which was growing in the same pot as the 

 preceding was pricked many times on the middle and apical portion of a leaf -blade about 3.5 inches 

 broad. 



There was no result from the inoculation. 



(158.) Pumpkin var. Nantucket Sugar. This vine was in the pot with 156 and 157. 

 pricks were made on the middle and apical part of a blade about 2.5 inches broad. 

 There was no result from the inoculation. 



(159.) Pumpkin var. Nantucket Sugar. Many pricks were made on the apical part of a leaf- 

 blade about 2 inches broad. 



There was no result from the inoculation. 



(160.) Pumpkin var. Nantucket Sugar. This was growing in the pot with the preceding. 



pricks were made on the apical portion of 

 a leaf-blade about 2 inches broad. 

 No disease resulted. 

 (161.) Pumpkin var. Nantucket 

 Sugar. Many pricks were made on the 

 apical portion of a leaf-blade about 3 

 inches broad. 

 No result. 



(162.) Pumpkin var. Nantucket 

 Sugar. This vine was growing in the pot 

 with 161. Many pricks were made on 

 one side of a leaf-blade about 4 inches 

 broad. 



No result. 



(163.) Watermelon {Citrullus vul- 

 garis). This vine, which was planted 

 March 12, was pricked many times on a 

 side lobe of a leaf -blade about 1.75 inches 

 broad. 



There was no result from the inocula- 

 tion. 



(164.) Watermelon. This vine was 

 about a month old. Many pricks were 

 made on the apical part of a leaf-blade 

 about I inch broad. 

 No result. 

 (165.) Watermelon. This vine was 

 the same age as the preceding. Many pricks were made on the middle lobe on one side of a leaf- 

 blade about 1.25 inches in diameter. 

 No result. 



(166.) Watermelon. This was growing in the pot with the preceding. Many pricks were made 

 on the middle and basal lobes on one side of a leaf-blade about 2 inches broad. 

 No result. 



(167.) Muskmelon var. Shumway's Giant. About 20 pricks were made in the center of a 

 leaf -blade over 2 inches broad. The pricks were in a space not over 5 mm. in diameter, and to each 

 side of the midrib. The fifth day (9 a. m.) the first trace of wilt appeared. It extended in a narrow 

 line along the midrib from the pricked area to the tip. It was most noticeable at the extreme tip. 

 At 2 p. m. the apical one-sixth of the leaf-blade had wilted in a V-shaped area from the pricked part 

 outward. The wilt did not yet extend downward beyond the pricked area more than 1.5 mm. The 

 next afternoon about one-third of the pricked leaf-blade (apical part) had wilted and changed color. 

 The seventh day there was no change. The next morning the blade of the first leaf down and of the 

 first leaf up had wilted. The petioles were rigid. About two-thirds of the blade of the pricked leaf 

 was flabby. The ninth day the cotyledon under the pricked leaf had wilted. The opposite one was 

 green and turgid. The second leaf up was flabby. The leaves of the bud were still normal although 



Fig. 69.* 



*FiG. 69. — Cross-section of middle of a muskmelon petiole.showing a bundle disorganized hy Bacillus tracheiphilus 

 with the formation of a large cavity. From inoculated plant No. 150. Drawn from a paraffin infiltrated stained 

 .section. Slide No. 208 A 9. 



