EUROPEAN FOULBROOD. 



21 



RESISTANCE OF BACILLUS PLUTON IN HONEY TO DIRECT 



SUNLIGHT 



Experiments were made to determine the resistance of Bacillus 

 pluton when suspended in honey to the direct rays of the sun. 

 In these experiments a honey suspension of the organism obtained 

 from the stomachs of infected bees is exposed to the sun in a 

 Petri dish Avith the top removed. After intervals, reckoned in hours, 

 inocuhition tests are made using healthy larvae and the direct 

 method. Table VIII contains a summary of the experiments per- 

 formed : 



Taulk VIII. — Resistance of Bacillus pluton suspended in honey and exposed 



to direct sunlight 



Date of inoculation. 



Results of Inoculation. 



1915. 

 Aug. 24 



Do 



Do 



Aug.3 



Aug. 20 



Sept. 13 



Sept. 19 



Aug. 20 



Sept.l4 



Do 



Sept.ll 



Sept.l4 



Do 



Sept. 28 



European foulbrood produced. 



Do. 



Do. 

 No disease produced. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



It is shown by the experiments recorded in Table VIII that in 

 direct sunlight Bacillus pluton was destroyed in from 3 to 4 hours. 



The results obtained by the experiments summarized in the last 

 three tables above, it will be noted, show that Bacillus pluton is sus- 

 ceptible to the destructive effects of the direct rays of the sun ; that 

 the resistance of the organism suspended in honey is about equal to its 

 resistance when suspended in water; and when dry the resistance is 

 considerably greater than when suspended in either water or honey. 

 It is to be expected that the period required for the destruction of the 

 organism by the rays of the sun will vary with the intensity of the 

 rays at the time of the exposure. In the foregoing experiments clear 

 days were chosen and preference was given to the middle of the day 

 for the exposures. 



RESISTANCE OF BACILLUS PLUTON TO FERMENTATION 



In obtaining data relative to the resistance of Bacillus pluton to 

 fermentation, the stomach contents of larvae sick or recently dead of 

 European foulbrood Avere suspended in a 10 per cent sugar (saccha- 



