LIST OF ILLUSTRATIONS XIX 



Page 



123. Tobacco leaf attacked by Bacterium solanacearum 180 



124. Inoculated young tobacco plant attacked by Bacterium solanacearum. . . 181 



125. Dwarf nasturtium attacked by Bacterium solanacearum 182 



126. A. Common garden balsam attacked by Bacterium solanacearum. B. 



Stem of same enlarged 183 



127. Dwarfing of Ricinus due to Bacterium solanacearum 184 



128. A, B. Sunflowers destroyed by Bacterium solanacearum 185 



129. Cross-section of a mature potato tuber showing vascular invasion by 



Bacterium solanacearum 186 



130. Petiole of Tropaeolum majus (nasturtium) attacked by Bacterium 



solanacearum. Inoculation on stem at A' 187 



131. Dwarfing of Helianthus annuus due to Bacterium solanacearum. Checks 



at right and left 189 



132. Appearance of Bacterium solanacearum on agar poured plates 190 



133. Fluid character of colonies of Bacterium solanacearum on agar plates. . . . 191 



134. Flagellate rods of Bacterium solanacearum: a, East Indian origin; h, 



American origin 192 



135. Stabs of Bacterium solanacearum in nutrient + 10 gelatin 192 



136. Cross-section of a young potato tuber showing removal of starch from 



the areas infected by Bacterium solanacearum 193 



137. Infected potato stem in longitudinal section. Early stage. Bacterium 



solanacearum confined to a single vessel 194 



138. Beginning of a bacterial cavity (around a vessel) in stem of a potato 



plant inoculated on a leaflet with Bacterium solanacearum 196 



139. Empty and bacterially occluded vessel in a potato plant. Result of a 



stem inoculation 197 



140. Bacteria from same series as figure 139, highly magnified 198 



141. Tomato stem in cross-section, showing origin and structure of two 



incipient roots — result of an inoculation 199 



142. Tyloses in vessels of a potato stem attacked by Bacterium solanacearum. 



Bacteria at X 200 



143. Tomato plant attacked by Apkmobacter michiganense EFS, as result of 



needle-prick inoculation 203 



144. Tomato plants inoculated one month with a pure culture of Aplanobacter 



michiganense. Massachusetts organism. 1915, colony A. Check 

 plants in background 204 



145. Stems of tomato plants showing only a slight tendency to form roots 



when inoculated (over 3 months) with Aplanobacter michiganense . . . 205 



146. Tomato leaf showing irregular withering of leaflets dwe io Aplanobacter 



michiganense. Inoculated in the stem 206 



147. Tomato stem in cross-section showing an incipient root destroyed from 



within (the black part) by Aplanobacter michiganense 207 



148. A, B. Tomato stem in cross-section showing large cavities in the phloem 



as a result of inoculating Aplanobacter michiganense 208 



149. Longitudinal section of a tomato stem attacked by Aplanobacter michi- 



ganense in the sieve-tube region 209 



150. Cross-section of a small group of sieve-tubes in a tomato stem showing 



sieve-plates, and disintegration of the phloem by Aplanobacter michi- 

 ganense 209 



