LIST OF ILLUSTRATIONS XXI 



Page 



182. Bacillus carotovorus in gelatin — buried colonies 24 hours old, showing 



root-like outgrowths 240 



183. A, Bacillus carotovorus and B, Bacillus apiovorus in gelatin stabs 241 



184. Behavior of soft rot bacteria in peptone beef bouillon with ten per 



cent ethyl alcohol 242 



185. Rot of celery due to Bacillus apiovorus Wormald 244 



186. Resistance of potato shoots to Bacillus apiovorus 245 



187. A, B, C. Three photomicrographs of flagella of Bacillus aroidece Towns- 



end 247 



188. Bacillus aroideae after 8 days on raw carrot 248 



189. A, B. Gas in milk produced by Bacillus aroideae — all CO- 250 



190. Curling of potato leaflets when stem is attacked by Bacillus phyioph- 



thorus Appel 253 



191. Potato stems attacked by basal stem rot due to Bacillus phytophthorus — 



48 hours 254 



192. Same as figure 191 but after another 48 hours 254 



193. Inoculated potato plant destroyed by Bacillus phytophthorus — 7 days.. . 255 



194. Potato shoot attacked by Bacillus phytophihoriis—i3 hours 256 



195. Shoots of White McCormick potato inoculated with Bacillus phytoph- 



thorus in 1915. Control plants in the background 258 



196. Same as figure 195, but two days later 259 



197. Woody base of figure 193 two days later. Sound mother tuber at 



right 260 



198. Bacillus phytophthorus: same as figure 195, l)ut the inoculations are on 



older, more resistant shoots 261 



199. Same as in figure 195, but 19 days later — new shoots growing up from 



the undestroyed base 262 



200. Enlarged cross-section of figure 193, well above the inoculated part. 



Bacteria in a vessel 263 



201. Bacillus phytophthorus attacking the cut surface of a raw potato 264 



202. Lenticel infection in a potato tuber due to Bacillus melaiiogenes P. and M. 265 



203. Very early stage of decay in potato tuber under a sound skin — lenticel 



infection like figure 202 266 



204. Flagellate rods of Bacillus phytophthorus 267 



205. a. Gelatin colonies of Bacillus carotovorus with (6) those of Bacillus 



phytophthorus for comparison. Natural size 269 



206. Gelatin plate cultures of Bacillus phytophthorus from a South Carolina 



potato, 1917 270 



207. Bacillus phytophthorus on gelatin — a surface colony magnified to show the 



fimbriate margin 271 



208. Bacillus phytophthorus in gelatin — 2 buried colonies, magnified 271 



209. Bacillus phytophthorus. — Small buried colony in gelatin 5 days at 16° C, 



showing lenticulate coronal colonies in the gelatin 272 



210. Effect of ethyl alcohol on Bacillus phytophthorus and Bacillus carotovorus 



in peptone bouillon 273 



211. Inoculations showing virulence of Bacillus phytophthorus (Appel I) 



after 13 years on culture media 275 



212. Gelatin plate culture of Bacillus carotovorus. B. Cross-section of 



Tropaeolum stem attacked by Bacterium solanacearum 276 



