32 THE UNIVERSITY SCIENCE BULLETIN. 



DISCUSSION. 



It will be observed that by Fonte's method all of the members 

 of the acid -fast group of organisms growing on culture media 

 saprophytically were decolorized. This includes the pure cultures 

 of the tubercle bacillus. None of the other methods would com- 

 pletely decolorize any of the members of this group of organisms, 

 Bunge and Trantenroth 's and Pappenheim's having as a rule a 

 greater efficiency than Gabbet's or the Ziehl-Neelsen method, but 

 even with these there were always some organisms of each member 

 of the group retaining the fuchsin stain. On the other hand, in 

 twenty-nine positive sputums from clinical cases of tuberculosis 

 the tubercle bacilli remained acid-fast by Fonte's method as well 

 as by the other methods. One sample of sputum from a doubtful 

 case of tuberculosis (8), however, which when examined by Fonte's 

 method allowed only a few weakly acid-fast organisms containing 

 the characteristic blue granules, appeared entirely different by 

 the Ziehl-Neelsen and other methods, showing by these fifty and 

 seventy-five strongly acid-fast organisms per field. This sputum 

 was treated for a few minutes with 15 per cent antiformin, and 

 after repeated washings the sediment was injected into guinea 

 pigs. The injected sediment was rich in acid-fast organisms by 

 the Ziehl-Neelsen method. Aftei' three months the pigs were 

 normal in weight, did not respond to the tuberculin test, and at 

 post mortem showed no evidence of tuberculosis except for the 

 slight enlargement of a few mesenteric lymph glands. The tissue 

 examination was negative. A similar report can be made in re- 

 gard to urine sample (9), where many strongly acid-fast organ- 

 isms were found by Gabbet's, Ziehl-Neelsen 's, Pappenheim's, 

 and Bunge and Trantenroth 's methods, while only a few very 

 weakly acid -fast organisms were in evidence by Fonte's method. 

 Animal inoculation gave negative results. Clinically this case is 

 not tuberculosis at present. In regard to the action of these two 

 strains of acid-fast organisms one of the following must be true: 

 (1) That the organisms are not tubercle bacilli; (2) that if they 

 are they are so avirulent as not to cause tuberculosis in guinea 

 pigs; (3) that the guinea pigs were unusually resistant to tubercle 

 bacilli ; (4) that the bacteria were attenuated or killed by the anti- 

 formin. In view of the fact that saprophytic acid-fast organisms 

 have been isolated from sputums and urines, that guinea pigs ai'e 

 considered very susceptible to the tubercle bacillus, that the anti- 

 formin did not injure their acid-fast properties and is generally 



