REPORT OF THE SOCIETY 109 



coming dry and having a somewhat granular appearance. Althogh the entire 

 central part of the rhizome is totally disintegrated, the tough epidermis 

 remains comparatively unchanged. 



The most advanced stages of the disease are characterized by a dead shoot, 

 at the base of which is found a badly affected rhizome. The younger parts are 

 reduced to a dark brown granular mass, with a musty odour, which can be easily 

 separated from the remainder of the rhizome. 



Observations show that the irifection is rather local in the plant, afad not 

 transmitted from one part to another through the rhizome. Unless the weather 

 is extremely favourable, only infected shoots succumb to the disease, the remain- 

 der of the plant remaining unaffected. It is the opinion of the writer that the 

 disease is transmitted from one shoot to another through the intervening soil. 

 This was proved by the examination of plants with diseased and healthy shoots, 

 which showed that the only infection that occurred to the healthy shoots was an 

 occasional wilting of their outer leaVes, indicating that the pathogen travelled 

 through the soil and not through the rhizome. 



Etiology. 



Isolation of Organisms. 



The writer obtained in pure culture thirtj'^-two organisms from soft rot 

 lesions of different plants. Of these twenty were from Iris, six from turnip, 

 four from cabbage, and two from onion. 



In addition, pure cultures of Bacillus carotovorus from Wisconsin and Onta- 

 rio Agricultural Collets, were placed at the writer's disposal. 



The standard technique was used in the isolation of the pathogens from 

 diseased tissues. Young newly infected parts were thoroughl}^ disinfected, 

 then small particles of the inner tissue removed to sterile water blanks from 

 which plates were poured. After the incubation of these plates, cultures were 

 made from individual colonies. In no case were there more than two different 

 types of colonies on the same plate. In cases where there were more than one, 

 each was isolated separately and labelled with an additional a, or b, after the 

 original culture number. 



The medium used in all cases was a 2% Iris leaf infusion agar made up 

 according to the following formula: — 



Iris leaf infusion 500 c.c. 



Dextrose 20 gms. 



Agar 20 gms. 



Distilled water 500 c.c. 



