218 The Celery -Rot Bacillns 



wurzel a slight discoloration was produced round the point of inocula- 

 tion but there was no definite rot. 



Action on ivhole Roots and Tubers. The bacilli were transferred 

 from a streak culture with a platinum loop to the spots selected for 

 inoculation and two or three pricks were made through the bacterial 

 slime with sterile needles; control spots were punctured without the 

 application of the bacteria. The results were as follows: — 



Radishes. Slight discoloration round the inoculated wounds but 

 no definite rot, though after eleven days round one point of inoculation 

 there was a whitish slime containing numerous bacteria. 



Potatoes. Slight discoloration at points of inoculation but no rot. 



Carrots. Slight discoloration on the fifth day after which the rot 

 progressed from each point of inoculation and after eleven days from 

 the commencement of the experiment the affected areas (dark brown 

 in colour) round the four inoculated spots were from ()-6 to 2-7 cm. 

 in diameter. 



Artichokes. A blackening of the tissues immediately round the 

 inoculated spots (but not round the controls) was noticed after a few 

 days but no rot had set in after eleven days. 



Parsnips. Slight browning round the inoculated punctures but 

 no rot. 



Turnijys. Readily attacked ; at the end of eight days almost 

 wholly destroyed. . 



Swedes. These proved more resistant than turnips, for though the 

 tissues in the immediate neighbourhood of the inoculated punctures 

 were destroyed, lateral extension of the rot was soon arrested, and it 

 proceeded inward only to about the same depth to which the needle 

 had penetrated. 



Mangel-tvurzels. Appeared quite resistant, the only perceptible 

 change being a "bleeding" at the wounds which however occurred 

 to the same extent also at the control spots. 



Inoculation Experiments on Growing Plants. Leaves of plants 

 growing in pots of rape, turnip, parsley, carrot, parsnip, radish, swede, 

 cabbage and broccoli were inoculated. In one experiment the plants 

 were kept in a greenhouse, in another they were placed in the open. 

 In nearly every instance inoculation with the bacillus resulted in an 

 increase in the size of the wound, usually accompanied by a longitudinal 

 splitting, but the leaves were not destroyed except in parsley and carrot, 

 though the rot made some progress in one leaf of broccoli and one 

 of swede. 



