PATHOGENIC STREPTOTHRICES. 359 



hypersemia, with the coincident exudation and infiltra- 

 tion of cellular elements, probably aids in the isolation 

 or casting off of the tuberculous nodule, the inflamma- 

 tory zone forming, so to speak, a line of demarcation 

 between the diseased and healthy tissue. 



As a curative agent for the treatment of tuberculosis, 

 tuberculin has not merited the confidence that was at 

 first accorded to it. Its field of usefulness is now 

 almost limited to the diagnosis of obscure cases, and 

 even for this purpose it is less frequently employed 

 than formerly. 



In veterinary medicine it has proved much more 

 trustworthy as a diagnostic aid, and is practically 

 everywhere in use for the detection of incipient tuber- 

 culosis, especially in cattle. 



PATHOGENIC STEEPTOTHEICES. 



The term streptothrix is restricted to a group of 

 organisms having morphological affinities with the bac- 

 teria on the one hand and the hyphomycetes on the 

 other. They resemble the bactei-ia in that they occur 

 as homogeneous threads which under artificial cultiva- 

 tion may become segmented into short bacillus- or 

 coccus-like fragments. Furthermore, they are unlike 

 the moulds in that they have not a double wall ; are not 

 filled with fluid containing granules, and the segments 

 are not separated from one another by a distinct parti- 

 tion. They simulate the moulds in that they develop 

 from spores into dichotomously branching threads, 

 which ultimately form colonies having more or less 

 resemblance to true mycelia. Certain of the threads 

 composing such a mycelium become fruit hyphae, break- 

 ing up into round, glistening, spore-like bodies. As a 



