230 



BACTERIA IN RELATION TO PLANT DISEASES. 



(29.) The sixth leaf from the tip was pricked many times. The pricks were made along the 

 midrib and in the mid-basal part of the blade. The first signs were noted at 10 a. m., October 31. 

 Two-thirds of the pricked leaf hung down flaccid (that part beyond the pricked area) . The rest 

 of the vine was normal. The following day the inoculated leaf-blade had entirely collapsed and 

 was hanging down. It was dry-shriveling but still green. The petiole was turgid. The eighth 

 day the pricked leaf-blade was wholly dry-shriveled. At noon of the ninth day the petiole of 

 the pricked leaf was flabby and shriveled nearly to the base but was still green. The first leaf 



Fig. 62.* 



above had become flabby also. Twenty-four hours later the blade of the pricked leaf was wholly 

 brown-shriveled, and its petiole much as before, i.e., shriveled nearly to the base. The second leaf 

 above had become flabby and was drooping. The first leaf below, which was separated from the 

 pricked one by a long internode, was still turgid. The eleventh day (a. m.) the second leaf above was 

 wholly flabby and drooping. The tip of the third leaf above was also flabby and drooping. The 



inner phloem of an 



Fig. 62.— Segment of a cucumber-stem attacked by Bacillus Iracheiphilus: Cross-section (ir 

 outer bundle to surface of stem) after fixing in absolute alcohol. All the spiral vessels are occupied, also two pitted 

 vessels. Bacterial cavities in primary vessel parenchyma. Bacterial masses and softer tissues contracted by alcohol. 

 Anacostia, D. C, July 21, 1903, Drawn from stained section with aid of Abbe camera Slide 178-5 



