REPOKT OF THE SOCIETY 113 



culated were as before placed under bell jars in the greenhouse at a temper- 

 ature ranging from 65°.70T. (18°— 22°C). 



Eight days after inoculation, several plants, namely, IbC, 7al, 15C, and 

 19b showed definite signs of infection, the outer leaf blade in all cases being 

 definitely watersoaked. At the end of twelve days no increase in infection was 

 noted, except that 7al had developed so as to exhibit definite symptoms of the 

 disease, one shoot being entirely wilted. From an infected leaf of the above 

 plant six re-isolations were taken and labelled 71-76. These re-isolations were 

 made to agar slants, allowed to grow for one day at 27"C, then plates were 

 poured and sngle colony pure cultures obtained. On February 24th., plants 

 were inoculated with one-day old beef broth cultures of the organisms 71-76 

 inclusive in the same manner as previously described. Four days after inocu- 

 lation definite symptoms were visible on plants 72 and 74. After four weeks 

 the entire plants had become diseased. On March 3rd., seven days after ino- 

 culation, plants 73 and 75 also showed definite symptoms of the disease. Besi- 

 des the usual watersoaking of the leaves, plant 73 showed a dark gray bacterial 

 ooze exuding from the base of the infected shoot. 



On March 10th., plants were again inoculated with twenty-four hour old 

 beef broth cultures of organisms laC, 4, 10, 15C, 19b and 26b. After four day 

 19b showed definite symptoms of the disease. After seventeen days the plans 

 had become entirely diseased and almost totally wilted. From young newlt 

 infected leaves of this plant, five re-isolations were taken and numbered consey 

 cutively from 191-195. The poured plate method was used to obtain pure- 

 cultures, after which the organisms were used for re-inoculation purposes. 



As a final test for the pathogenicity of the organisms, it was decided to try 

 inoculations on plants which had been grown under afbsolutely sterile condi- 

 tions. The sterile plants were obtaiined in the following manner; Iris plants 

 about twelve inches high were taken from pots growing in the greenhouse and 

 the soil entirely removed from the roots by washing in tap water aind scrubbing 

 with a smajl b ush. These plants were then wasihed in a 1-1000 mercuric chlo- 

 ride solution, after which they were thoroughly rinsed in two changes of sterile 

 water. The pots used for transplanting were four inch pots which had been 

 thoroughly scrubbed and then soaked \n mercuric chloride for ten mi'nutes. As 

 a soil, pure sand was used whiph had been previously autoclaved for two hours 

 at eighteen pounds pressure. The sterile plants were placed in the sterilized 

 pots which contained the sterilized sand and were then watered with sterile 

 water, and kept till ready for inoculating. 



The organisms used for inoculating were 721, 191, and 74. Agar slope cul- 

 tures twenty-four hours old were used and the plants inoculated by means of 

 needle pricks just below the surface of the sand. After inoculation the plants 



