216 MICRO-ORGANISMS AND DISEASE. [CHAP. 



mice dying from anthrax after inoculation with cultures of 

 hay bacillus, but I question the admissibility of his interpre- 

 tation. I believe that some accidental contamination of the 

 culture of hay bacillus with anthrax spores or otherwise may 

 have occurred and have got overlooked. How liable one 

 kind of infective material is to be invaded by foreign infective 

 matter may be understood from the following examples of 

 its actual occurrence. 



It is now admitted on all hands that the results of 

 Villemin in producing what is called artificial tuberculosis in 

 guinea-pigs, by inoculating the animals subcutaneously with 

 cheesy matter derived from human and bovine tuberculosis 

 or from a guinea-pig suffering from artificial tuberculosis, 

 cannot be produced by any other means ; it cannot be pro- 

 duced by ordinary, i.e. non-tubercular cheesy or other pus, 1 

 nor by setons (as once thought by Wilson Fox and Sanderson) 

 setting up chronic caseous inflammations in the skin of 

 guinea-pigs, nor by chronic mechanical irritation, e.g. inser- 

 tion into the peritoneal cavity of bits of gutta-percha or 

 other substances producing chronic peritonitis (as was 

 thought by Cohnheim and Fraenkel), but, as Cohnheim 

 now tersely puts it, tuberculosis can be produced only by 

 matter derived from a tuberculous source, and anything 

 that produces this tuberculosis is derived from a tuberculous 

 source. Dr. Wilson Fox, after the very important experi- 

 ments performed by Dr. Dawson Williams, according to 

 which chronic inflammation in the skin of guinea-pigs 

 produced by setons, is in no case followed by tuberculosis, 

 has conceded that in his earlier experiments there must have 

 entered some error in the use of the materials. Cohnheim 

 has conceded the same. It is clear that these observers, 

 while working at the same period with both tuberculous and 

 1 Compare Watson Cheyne, Practitioner, April 1883. 



