AMERICAN FOULBROOD. 27 



Table VI. — American foulbroqd spores heated in undiluted honey 



Temperature. 



Period of 

 heating. 



Origin of sample. 



Cultural results. April-May, 1915. 



°C. 



100 



°F. 

 212 

 212 

 212 

 212 

 212 

 212 

 217 

 221 

 221 

 225 

 225 

 225 



Minutes. 

 10 

 10 

 10 

 20 

 20 

 20 

 25 

 20 

 20 

 20 

 30 

 40 



Cuba 



Numerous spores not killed. 



100 





Do. 



100 



Ohio 



Do. 



100 



Cuba 



Do. 



100 





Do. 



100 



Ohio 



Do. 



103 





Do. 



105 



do 



Do. 



105 



Cuba . 



Do. 



107 



do 



Do. 



107 



do 



Do. 



107 



do 



Do. 









From the results given in Table VI it will be observed that in every 

 instance the spores suspended in honey resisted 100° C. for more than 

 10 minutes. It will be noted that numerous spores were alive after 

 being so heated for 20 minutes. In fact they resisted 105° C. for 20 

 minutes and more. It is shown that numerous spores from the re- 

 sistant Cuban sample were still alive after 40 minutes heating at 107° 

 C. When suspended in honey, therefore, spores are much more re- 

 sistant to heat than when suspended in water (p. 22) or when sus- 

 pended in diluted honey (p. 26). 



While the thermal death point has not been definitely determined 

 for the spores suspended in honey, the results obtained indicate that 

 the point was being approached by the experiments of Table VI. It 

 was found that the spores suspended in honey were killed readily 

 by heating in the autoclave at 15 pounds pressure, being destroyed, 

 in fact, by the time this pressure was reached. In making these tests 

 the suspension in test tubes was brought to 100° C. before being 

 placed in the autoclave. After the heating cultures were made. 



SPORES HEATED IN HONEY AND FED TO BEES 



A further set of experiments was made in which American f oulbrood 

 material suspended in honey was heated to 100° C. and tested by the 

 inoculation of colonies of bees. In performing the experiments a 

 concentrated aqueous suspension of the disease material was added to 

 hot honey, which is handled more readily than the cooler honey, until 

 each 1 5 c.c. of honey suspension contained the material from 3 to 5 scales . 

 This was then distributed in test tubes, each tube receiving about 15 

 c.c. of the suspension. These tubes were heated as were the aqueous 

 suspensions in experiments reported above (p. 22) , by immersing them 

 in water. After heating, the contents of the tube were added to sirup 

 and colonies were inoculated. In Table VII some of the experiments 

 performed are summarized : 



