ORGANISMS RESEMBLING . TUBERCULOSIS. 363 



the color even under the action of strong decolorizing- 

 agents. 



We have reviewed the three common pathogenic 

 organisms that may be encountered in the sputum of 

 tuberculous individuals. Occasionally other species may 

 be present. The pyogenic forms are not rarely found, 

 and for some time after an attack of diphtheria the 

 bacillus of Loffler is demonstrable in the pharynx, so 

 that it, too, may be present under exceptional circum- 

 stances. 



ORGANISMS WITH WHICH BACTERIUM TUBERCULOSIS 

 MAY BE CONFUSED. 



It is important to note that in the study of tubercu- 

 losis one may fall into error unless it be borne in mind 

 that there is a group of bacilli whose members are in 

 many respects so like the genuine bacillus tuberculosis 

 as easily to be mistaken for it. While its peculiar 

 micro-chemical reaction is usually sufficient for identifi- 

 cation, particularly in connection with human patho- 

 logical lesions, it is well to remember that the confusing 

 organisms are not only characterized by the same stain- 

 ing peculiarities as bacillus tuberculosis, but may readily 

 be mistaken for it on morphological grounds also. 

 Furthermore, while not all the members of this group 

 are capable of causing disease, some of them are patho- 

 genic for the same animals that are susceptible to true 

 tubercular infection ; and these may produce in those 

 animals lesions which are distinguishable from genuine 

 tubercles only by their finer histological structure. A 

 few words concerning some of these varieties, with a 

 brief summary of their more important peculiarities, 

 may not be out of place. 



