14 



■withdrawn from the boiling water at stated intervals, were cooled and incu- 

 bated. 



Results 1. Spores from a seven months old culture in bouillon were 

 killed at a temperature of 100° in 1 hour and 20 minutes. 



2. Spores from a 2J months old culture on agar were killed in two hours 

 and a half. 



3. Spores from agar nine days old, — -slight' growth after 2 hours and 45 

 minutes ; no growth after three hours. 



4. Spores 14 days old and 21 days old, — in each case after two hours 

 boiling, one of the duplicate tubes formed a growth ; another after 2| hours, 

 whilst the remainder had no growth. All were killed in 3 hours. 



I used also fine capillary glass tubes. A suspension of the spores in 

 water was drawn up into sterile tubes, which were then sealed at both ends, 

 The tubes were placed in boiling water and withdrawn at stated intervals. 

 The contents of the tubes were then introduced into agar, which was incu- 

 bated at 37''0. ; and great care was taken to have a suspension *of the spores 

 by fihering them through glass wool. 



The results were : With a temperature of 98°C. (about the boiling point 

 in this locality), spores from a 7 days' old culture on agar were killed in 2f 

 hours ; and spores from agar 9 days old were killed in 3 hours. 

 £;;^7 Another experiment was made to determine the thermal death point in 

 honey. The honey was of two kinds, clover and backwheat, The former 

 had a specific gravity of 1.042 at 60°C. and contained 0.0S7% of formic acid, 

 while the latter had a specific gravity of 1.040 at GCC. and contained 0.170% 

 of for jiic acid. The spores used were from agar three weeks old, and three 

 methods were followed : 



1. Silk threads with dry spores thereon ; 2. Test tubes containing honey 

 with a heavy inoculation of spores ; 3. Capillary tubes containing a suspen- 

 sion of spores in distilled water. The spores used were not filtered through 

 sterile glass wool, as it seemed desirable to imitate as far as possible the con- 

 ditions met with in infected honey. The following are the results : 



1. Silk threads with dried spores, from an agar culture two weeks old. 



Time. Temperature. Repult. 



15 minutes 115''G growth. 



30 " 113 " " 



45 " 115 " 



60 " 113 " " 



1 hour 15 minutes . . . 114 " •' 



1 " 30 " .. 115 " " 



1 "45 " .. 115 " 



2 hours 114 " " 



2 " 15 minutes... 116" " 



2 "30 " .. 115 " 



2 " 46 " .. 115 " no growth. 



2. Tubes containing honey and spores mixed together. 



30 minutes 115°C growth. 



45 " 114 " « 



60 " 114 " " 



1 hour 15 minutes . . . 114 " " 



1 '• 30 " .. 114 " " 



1 " 45 " .. 115 " 



