136 THE ROYAL SOCIETY OF CANADA 



mal death point of tubercle bacilli. The culture method becomes thus 

 the most convenient, and at the same time the only indisputable way of 

 ascertaining the resistance of these bacilli to heat. The following 

 table represents the results of tests of the same character as those 

 undertaken with the endospores and the gonidia. 



55°C. 55°C. 58°C. 65°C. 70°C. 

 15 Min. 30 min. 60 min. 10 min. 10 min. 



B. tuberculosis (typas humanus) La- 

 boratory culture + — — — — 



B. tuberculosis (Wherry's strain) . . . . + — — — — 



Diphi heroid Bacillus Irom Hodgkin's 



Disease (Dr. Rhea) + — — — — 



It is clear from the above observations that these bodies seen in 

 tubercle bacilli, as also in the diphtheroid bacilli at times from Hodg- 

 kin's disease are in the first place very much less resistant to moist 

 heat than are many of the obvious endospores studied in this series, 

 and in the second place, that their resistance is not greater than that 

 of ordinary non-granular or non-beaded tubercle bacilli. Wherry 

 has already come to the same conclusion with regard to strains studied 

 by him.^ The same has been the experience of most observers both as 

 regards the resistance to heat, and the resistance to chemicals. 



Thus to take one who is perhaps the most careful and exact 

 bacteriologist of our time, Theobald Smith ^ finds that suspensions 

 of the caseous matter from bovine tuberculosis exhibits no greater 

 heat resistance than does a suspension of active cultures of the bovine 

 bacilli, made upon blood serum, when both are suspended in bouillon. 

 Exposure to a temperature of 60°C. for twenty minutes was sufficient 

 to destroy the bacilli in both. So long ago as 1887 Sternberg^ found 

 that tuberculosis sputum exposed to 60°C. for ten minutes was^inocuous 

 when injected into guinea pigs. Grancher and Ledoux-lebard^ 

 note that avian tubercle bacilli are killed by exposure of twenty minutes 

 at 60°C., but not of ten minutes, human bacilli were found dead after 

 an exposure of ten minutes. 'Bonhoff ^ found a culture of the human 

 tubercle bacillus in glycerinated broth was killed by an exposure of 

 twenty minutes to 60°C., and more recently Rosenau ^ comes to a 



1 "When suspended 0-85 percent. NaCl. solution these cultures were not killed 

 at 15 minutes nor 30 minutes at 55 °C., but were killed by heating to 60°C. for 15 

 minutes." (Jour. Infect. Diseases, Vol. XIII, 1913, 114.) 



"^ Theobald Smith, loc. cit. 



^ "Disinfection and Disinfectants." Report to the Amer. Public Health Assoc. 

 Concord, N.H., 1888, p. 148. ^ 



* Arch, de Med. Exper., Vol. IV, 1892, p. 1. 

 ^ Hygienische Rundschaw II, 1892, p. 100. 



• U. S. Treasury Dept., Hygienic Lab. Bulletin, No. 42, 1908. 



