LIST OF ILLUSTRATIONS XVll 



Page 



63. Squash plant wilted by Bacillus tracheiphilus 133 



64. Muskmelon plant wilted by Bacillus tracheiphilus 133 



65. Bacterially infected cucumber leaf gnawed by beetles. The infection 



preceded the gnawing 134 



66. Sound leaf locally infected by the gnawing of infected insects. The 



infection followed the gnawing 134 



67. Plant infected throughout as a result of insect gnawings like those 



shown in figure 66 135 



68. Flagellate rods of Bacillus tracheiphilus: a, b, X2000; c, XlOOO 136 



69. Enlarged colony of Bacillus tracheiphilus viewed by oblique transmitted 



light ,... 136 



70. Like fig. 69 but less magnification : internal colony markings of Bacillus 



tracheiphilus on an agar-poured plate, visible by oblique transmitted 

 light. Smooth on surface and homogeneous by direct transmitted 

 light 138 



71. Agar buried and surface colonies of Bacillus tracheiphilus by reflected 



light 140 



72. Leaf-stalk of an infected squash in cross-section 141 



73. Infected cucumber stem in cross-section 142 



74. A, Inner bundle of figure 73 enlarged; B, outer bundle of figure 73 



enlarged 142 



75. Infected cucumber stem in longitudinal section. Bundle destroyed .... 143 



76. Infected cucumber stem in longitudinal section showing empty and 



occluded spiral vessels 143 



77. Bacillus tracheiphilus highly magnified. From an infected cucumber 



vessel 143 



78. Cross-section of segment of a bacterially invaded pitted vessel. From a 



cucumber 144 



79. Field of cabbage in Wisconsin destroyed by black rot due to Bacterium 



campestre (Pammel) EFS 145 



80. Early stages of water-pore infection in cabbage. Natural size 146 



81. Vertical section through an infected water-pore on cabbage 146 



82. Section parallel to surface of a cabbage leaf-tooth showing occluded and 



empty water-pore 147 



83. Upper stoma (water-pore) of the preceding enlarged, showing the rod- 



shaped (bacterial) mass blocking the stoma 147 



84. Inoculated cabbage leaf showing black-veined marginal spots dvie to 



water-pore infection 148 



85. Middle of a cabbage leaf showing black-vein disease due to stem in- 



oculation 148 



86. A, B. Cabbage leaf -stalks in cross-section showing black bundles, due to 



Bacterium campestre 149 



87. Black bundles in fleshy part of kohlrabi, due to Bacterium campestre 149 



88. A, B. Flagellate rods of Bacterium campestre 150 



89. A, B. Colonies of Bacterium campestre on agar. XlO 150 



90. Buried and surface colonies of Bacterium campestre by direct transmitted 



light 151 



91. Agar colonies of Bacterium campestre by oblique transmitted light 152 



92. Cultures of Bacterium campestre and Bacterium phaseoli in Dunham's 



solution 153 



