262 MICRO-ORGANISMS AND DISEASE. [CHAI\ 



been done in this interesting field of research, important 

 because of its obviously great practical consequence. The 

 work hitherto done has been enormous, but, I fear, of less 

 utility than at first sight appears, for in most of it the point 

 most prominent in the mind of the worker was to ascertain 

 whether the particular antiseptic, mixed with the nourishing 

 medium in a solution of definite strength, has or has not the 

 power of inhibiting the growth of the micro-organisms. 

 This point no doubt is of some interest, and perhaps of 

 great interest, but whether a particular substance is an anti- 

 septic in the proper sense of the word, i.e. whether on ex- 

 posing the organisms to this substance in a solution of 

 definite strength and for a definite period, the organisms 

 become afterwards incapacitated from growing or multiply- 

 ing ; or still more, whether or not the substance is a 

 germicide, i.e. is capable of altogether annihilating the life of 

 the organisms ; these are questions which require special 

 attention, and represent a wide and rich field of inquiry ; 

 but, as far as I can see, have received only in very few 

 instances due attention. 



The disinfecting power of dry heat and steam on various pathogenic 

 and non-pathogenic organisms has been studied by Koch and his 

 coadjutors {Mittheil. atts. d. k. Gesundheifsamte, Berlin, 1881). Dr. 

 Parsons has described in the supplement to the fourteenth annual Report 

 of the Medical Officer of the Local Government Board, 1884, a series of 

 observations made conjointly with myself on the influence of dry heat 

 and steam on bacillus and spores of anthrax, bacillus of swine-fever and 

 bacillus of tuberculosis. Pieces of flannel received the fluids containing 

 the above organisms (separately), and were then exposed to heat. After 

 this the organisms were squeezed out of the flannel previously steeped in 

 salt solution, and this fluid was then injected into suitable animals and 

 the effect watched, and compared with the result of the inoculation wiih 

 the same materials not exposed to heat. The results of these experiments 

 were (/.^.p. 225) : " The spores of bacillus anthracis lost their pathogenic 

 power after exposure for four hours to a temperature a little over the 



