H. WORMALD 229 



Germicides in Celery Extract. 



In an endeavour to obtain information relative to the efficacy of 

 the antiseptics in controlling the disease, trials were made to test the 

 germicidal action of some of them. The poisonous properties of mer- 

 curic chloride and the relatively great bulk of alcohol, chloroform and 

 some others preclude the use of these in the practical application to 

 preventive measures. The results obtained in the preceding experi- 

 ments with copper sulphate compared unfavourably with other results ; 

 when however instead of the culture media then employed an extract 

 of celery is used its efficiency is increased since it was found on trial 

 that 0-1 % copper sulphate in this medium inhibited growth completely. 

 Copper sulphate therefore was selected for further trial ; others were 

 permanganate of potash, carbolic acid, lysol substitute and formalde- 

 hyde. Celery extract was the medium used in order to obtain cultural 

 conditions more nearly approaching those obtained in the host plant. 



In a preliminary experiment tubes of celery extract were prepared, 

 each containing 9 c.c. of the sterile solution, and inoculated. At the 

 end of 18 hours the tubes were distinctly turbid, thus giving evidence 

 that vigorous growth was in progress ; the germicides were then added 

 as in the previous experiments to give the proportions as shown in the 

 table. The tubes were shaken and a loopful (2 mm. loop) of the liquid 

 in each tube was transferred to a tube of sterile celery extract at 

 intervals of (1) one hour, (2) 24 hours, (3) three days after the treatment 

 with the germicide ; those cases in which growth occurred in the sub- 

 inoculated tubes are marked + and those which remained sterile — . 



Transfer at the end of 



The results show that copper sulphate at 0-1 % and formaldehyde 

 at 0-01 % are very germicidal, probably all the bacilli being killed within 

 an hour. The action of carbolic acid and lysol substitute at 0-2 % 

 and formaldehyde at 0-005 % is slow and requires more than 24 hours 

 to kill the organism. Permanganate of potash at 0-1 % on the other 

 hand is rapid in its primary action but apparently the subsequent 



