S. G. Paine 491 



accompanied by a brown stain in the tissue bordering the rotted area 

 and finally the whole of the unattacked tissue assumed a dark brown 

 to jet-black colour. 



Sterile Slices of other Vegetables. At 20° C. vigorous rotting was 

 produced in slices of carrot, white turnip, yellow turnip, celery, onion, 

 Jerusalem artichoke, parsnip and sugar-beet. At air temperature these 

 all rotted to a certain extent but much less rapidly than at 20° C, and 

 rotting was frequently checked as in the case of the potato by a protective 

 formation of cork. 



Cut Shoots of Potato and Bean (Viciafaba). Shoots of these two plants 

 placed in tubes containing 10 c.c. of a suspension of the organism in 

 distilled water and kept in a green-house at 54° to 57° F., commenced 

 to rot at the cut end on the second day. The rot accompanied by 

 characteristic blackening of the stem steadily advanced upwards, so 

 that after eight days a length of some four or five centimetres of the 

 stem had been completely decomposed. Controls under the same con- 

 ditions remained perfectly healthy for three weeks. 



Prick Infection of the Stem of growing Plants. The plants used had 

 been forced in pots during the winter in a green-house with a regulated 

 temperature of 54° to 57° F. When the infections were made the 

 plants inoculated had sturdy upright stems eight to ten millimetres in 

 diameter and twenty to twenty-five centimetres in height, but leaf pro- 

 duction was very meagre and some of the plants were showing signs of 

 precocious flowering. They were not very robust specimens but served 

 quite well for the purpose of this research. When infection was to be 

 made below the level of the soil this was removed to a depth of about 

 two inches and subsequent!}^ replaced. Before inoculation the stems 

 were washed with alcohol and allowed to dry, puncture infections were 

 then made with a stout platinum wire bearing the inoculating material, 

 and the stems were bound closely with one centimetre strips of tin 

 foil in order to protect the wounds against the entrance of soil and loss 

 of moisture. In all, ten plants were inoculated in this way, four below 

 and six above the level of the soil. In every case successful infection 

 resulted while control plants remained perfectly healthy. On three 

 occasions the organism was successfully re-isolated from such infected 

 stems. One typical experiment may be cited in detail. The stem of 

 a plant bearing one shoot only, 25 cms. in height and 8 mm. in diameter, 

 was inoculated as described one inch below the level of the soil with 

 material from a rotted potato slice. This culture had been incubated 

 over night at 20° C. and represented the eighth transfer from the original, 



