xvii.J SEPTIC AND PATHOGENIC ORGANISMS. 217 



non- tuberculous matter, must have had, in the course of 

 experiments with the latter substance, accidental contamina- 

 tion with the former, and hence had the guinea-pigs inoculated 

 by them with non-tuberculous matter nevertheless affected 

 with tuberculosis. Dr. Williams, who had no contamination 

 to fear, working with non-tuberculous matter only, had 

 consequently no accidental contamination. This shows us 

 how dangerous, as regards reliability of results, it is to work 

 in one laboratory with different infective materials at the 

 same period. 



I have myself experienced some very curious results 

 bearing on this very point. During the last year I have 

 seen the following cases of accidental contamination occur. 

 I work in the laboratory of the Brown Institution, which 

 comprises a suite of rooms. Although working extensively 

 on anthrax, I generally limit myself to one room only. A 

 friend of mine, who one day injected into a vein of a 

 guinea-pig blood taken from a blood-vessel of a dog 

 suffering from distemper, found, to his great disappointment, 

 the guinea-pig dead after two days under the typical 

 symptoms of anthrax, the blood of this animal teeming 

 with the characteristic bacilli. The hypodermic syringe 

 used in this experiment for injection had not been previously 

 used by me in my anthrax experiments, since I never use a 

 syringe in my inoculations, but only glass pipettes freshly 

 made and drawn out into a fine tube. The experiment was 

 performed in the room adjoining the one in which my 

 anthrax investigations were being carried on, but I was in 

 the habit of making every day a good many specimens of 

 anthrax cultivations and spores, so that there must have been 

 a good many of these spores distributed on the table and 

 floor, and probably found their way into the wound of the 

 guinea-pig at the time the above experiment was made. 



