238 The Celery-Rot Bacillus 



the tube. No gas was ever evolved in Durham's tubes containing 

 this solution. 



For some time it was considered that no acidity was developed in 

 this medium, repeated tests with litmus solution failing to indicate 

 what could be considered as evidence that an acid was produced. The 

 diffusion of the sediment through the liquid when the test was applied 

 rendered a comparison with control tubes unsatisfactory, and passing 

 the liquid through filter-paper failed to remove the suspended particles. 

 More recently however another method was adopted. The tubes (of 

 cultures a fortnight old) were placed in a water-bath which was then 

 heated to boiling point when the tubes were removed and the contents 

 filtered separately into other tubes through Swedish filter-paper. Six 

 drops of neutral litmus solution were then added to the clear filtrate 

 of each tube and also to the control tubes. An acid reaction, though 

 faint, could then be detected in the inoculated tubes particularly if 

 they were held, together with the control tubes, in such a way that the 

 observer looked down the open ends of the tubes upon a white surface. 



Since the celery-rot bacillus produces an acid from a glycerine 

 containing medium (as Uschinsky's Solution), it should receive the 

 number -0000002 instead of -0000003 as previously recorded (46) by 

 the present writer and its full group number becomes 221-1113522. 



This number approaches so nearly that of Bacillus carotovorus Jones 

 (221-1113022) as determined by Harding and Morse (ii) that it was 

 thought desirable to obtain this organism for comparison. I was able 

 to obtain a culture of this Bacillus from Professor V. H. Blackman 

 who kindly prepared and forwarded a sub-culture from a tube received 

 by him from Dr Erwin F. Smith, Plant Pathologist to the Department 

 of Agriculture in the United States, The two points on which a com- 

 parison was particularly required were (1) behaviour in Uschinsky's 

 solution, and (2) chromogenesis. 



From the tube of B. carotovorus (culture only two days old) two 

 successive sub-cultures were made Avithin five days on celery extract 

 agar. In contrast to the celery organism its growth on this medium 

 was comparatively slow and after 24 hours it was practically confined 

 to the line of streak instead of spreading laterally as is the case with 

 the celery bacillus. The difference in rate of growth of the two strains 

 on celery agar may be a varietal character; on the other hand it is 

 possible that the reaction of the carrot strain to vegetable decoctions 

 had become modified from continued growth on a meat extract medium. 



A difference was also to be observed when the two strains were 



