REPORT OF THE SOCIETY 115 



which had been rotted as a result of the inoculations with 72 and 191 isolations 

 were made, namely, 721 and 1912. These isolations were grown, pure cultures 

 made and with them another group of sterile plants was inoculated. Within a 

 week characteristic symptoms had appeared in both cases. Again from these 

 diseased plants isolations 7213 and 19122 were taken. No further inoculations 

 were required because the organisms 72 and 191 had been "proved up" on sterile 

 Iris plants. 



The following will show a comparison of the organisms studied as compared 

 with Bacillus carotovorus; 



B. carotovorue B. 221.1113022 



The writer's isolation , B. 221.1113021 



From the above numbers it appears that the pathogens studied have cha- 

 racters which resemble very closely those of Bacillus carotovorus (Jones). The 

 actual resemblance, however, as will be seen later, is not as close as these group 

 numbers appear to show. 



Detailed Study of the Organisms. 



In order to simplify the following discussion where no comparisons are 

 made, it will be taken for granted that the organisms described are similar to 

 Bacillus carotovorus. 



Morphology. 



The organisms studied were all rods with rounded ends, varying in length 

 from 1.3 mu. — 4 mu. and in width from. 5 mu.-l mu. Thisshows very litte- 

 varia^tion from B. carotovorus which averages .8 mu, 2 mu. (Marshall (7). In all 

 cases the organisms were actively motile by means of peritrichiate flagella. No 

 endospores or capsules were found and the presence of pseudozoogloea or invo- 

 lution forms \\)a3 not observed. The' organisms are Gram negative arid very 

 susceptible to aqueous stains. 



Broth. 



Growth in beef peptone broth was extremely profuse, with only a slight 

 pellicle and abundant sediment. 



Agar Slant. 



Growth was glistening, smooth, somewhat spreading and with a slight gray 

 colour. 



