36 



BULLETIN 431, U. S. DEPARTMENT OF AGRICULTURE. 



In these inoculations it will be observed that a temperature some- 

 what greater than 158° F. (70° C.) maintained for 10 minutes was 

 necessary to destroy the virus of sacbrood when it was suspended in 

 glycerine, while a temperature somewhat less than 140° F. (60° C.) 

 is sufficient to destroy it when suspended in water (p. 34). The same 

 technique was employed when glycerine was used as the suspending 

 medium as was employed when water was used as the medium. 

 The same stram of virus was used in both instances. The point 

 here illustrated is of special interest in connection with the heating 

 of honey containing the virus of sacbrood. 



HEATING REQUIRED TO DESTROY SACBROOD VIRUS WHEN SUSPENDED 



IN HONEY. 



From the results obtained by heating the virus of sacbrood in 

 glycerine as given above it might be expected that a higher tempera- 

 ture would be necessary to destroy the virus when it is suspended in 

 honey than when it is suspended in water. 



In determining the heating necessary to destroy the virus when 

 suspended in honey the technique followed was similar to that 

 employed when water and glycerine suspensions were used. The 

 virus used in the inoculations bearing the date 1915 was of the same 

 strain in all instances. 



Table III.- — Results obtained vjTien the virus of sacbrood was heated in honey. 



Date of inoculation. 



Temperature. 



Time of 

 heating. 



"F. 



"C. 



Minutes. 



140 



60 



10 



145 



63 



10 



149 



65 



10 



154 



68 



10 



156 



69 



10 



158 



70 



10 



158 



70 



10 



158 



70 



10 



160 



71 



10 



160 



71 



10 



163 



73 



10 



163 



73 



10 



167 



75 



10 



167 



75 



10 



176 



80 



10 



Results of inoculation. 



June 1, 1915. 

 June 11, 1915 



Do 



June 4, 1915. 

 June 24, 1915 



Do 



Junel, 1915. 

 June 18, 1915 

 July 3, 1915., 

 Aug. 28, 1915 

 Aug. 7, 1915. 

 Aug. 28, 1915 

 June 1, 1915. 

 Aug. 7, 1915. 

 June 1, 1915. 



Sacbrood produced. 



Do. 



Do. 



Do. 



Do. 



Do. 

 No disease produced. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



As shown by the results recorded in Table III, the virus of sacbrood 

 when suspended in honey was destroyed in 10 minutes at a tempera- 

 ture very near 158° F. (70° C). This temperature is more than 18° F. 

 (10° C.) greater than the temperature required to destroy in the same 

 time the virus when suspended in water and approximately equal to 

 that necessary to destroy it when suspended in glycerine. 



