H)i2\ FATE OF TUBERCLE BACILLI OUTSIDE THE ANIMAL BODY 349 



The tuberculosis produced in the two guinea pigs inoculated at 

 the fifth testing from the sample of standing water contained in 

 the cotton-stoppered bottle, was neither extensive nor severe. 

 Those from tlie running water had a higher virulence than the 

 tubercle bacilli in the standing water, but the tuberculosis produced 

 was not so severe as that from the former samples. It should be 

 noted that the time of killing these guinea pigs was much earlier, 

 and it may be for this reason alone that the virulence appeared 

 to be weakening. This fact was noted at the time of killing the 

 four guinea pigs inoculated with the bovine tubercle-bacilli-in- 

 fected waters, and so the two guinea pigs inoculated with water 

 infected with the tubercle bacilli of the human type were not killed 

 at this time. Thirteen days later one of these two guinea pigs 

 died with generalized tuberculosis. Unfortunately the death of 

 this guinea pig was not noted until a short time afterwards, and 

 it could not be determined whether tuberculosis was the only cause 

 of death. The other of the two guinea pigs inoculated with the 

 sample of water containing the human type was killed 72 days 

 later, and the examination showed severe generalized tuberculosis. 



Later, on the I47th day, we find severe generalized tuberculosis 

 produced from each of the three samples. After this date only 

 two more tests were made from the sample in the cotton-stoppered 

 bottle, one on the iSoth and the last one on the 2O2d day of ex- 

 posure. These two tests show the lessening of the virulence of 

 the germs : for from the former no tubercles could be noted 24 

 days later, when the two inoculated guinea pigs died of acute 

 infection; from the latter, one guinea pig died too early to make 

 the test; the other, killed 78 days after inoculation, showed only 

 a doubtful sign of tuberculosis. However, an inoculation of an 

 emulsion of the tissues from the point of inoculation and the right 

 superior inguinal glands produced, in a secondary guinea pig, gen- 

 eralized tuberculosis. From the diseased tissues of this guinea pig 

 an active culture was obtained. Thus no end point was reached 

 from the sample of standing water with the bovine tubercle bacilli 

 in the cotton-stoppered bottle. The other two samples, kept in 

 porous flower pots which were transferred to the pool in the court- 

 yard, remained alive for 441 days, but were dead on the 47Oth day. 



From the emulsion of the bovine type severe tuberculosis was 

 produced in the guinea pigs even in the last test in which these 

 germs were found alive. From the emulsion of the human type 

 only localized tuberculosis was produced at the last test. The sec- 

 ondary guinea pig inoculated from the diseased tissues of this last 

 test animal showed severe generalized tuberculosis, and cultures 

 from the diseased tissues of both the original and the secondary 

 test animal showed these germs to be active. No test made later 

 than this showed any indication of live tubercle bacilli. Five such 

 neirativc tests were made. 



