STREPTOTRICES. 393 



Like the moulds, they consist of cylindrical cells which 

 branch dichotomously and form radially arranged masses 

 or mycelia. Moreover, f ruit-hyphas develop and bear chains 

 of roundish spores or conidia. Many of these forms when 

 growing in the animal body or in pure culture form hard 

 masses which have a radial structure. 



The resemblance to the bacteria is especially evident 

 under the microscope. The filaments, unlike those of the 

 moulds, are extremely narrow about the same width as 

 the average bacterial cell. These threads branch freely and 

 are perfectly homogeneous, without any transverse division 

 into cells as in the case of the moulds. As the threads be- 

 come old they may break up into rod-, or coccus-like forms 

 not unlike bacteria. Even spiral forms may thus result. 

 This fragmentation of the filament is to be distinguished 

 from the segmentation process whereby the round spores 

 or conidia form on the ends of the fruit-hyphae. 



The spores of these organisms have not the resistance 

 of those of bacteria. Thus, in the case of the actinomyces 

 they are destroyed in 5 minutes at 75. Moreover, they are 

 stained readily by the simple anilin dyes and by Gram's 

 method. 



The diphtheria and tubercle bacilli undoubtedly belong 

 to this -group, although their predominant characteristics 

 are those of bacteria. Nevertheless, branching forms have 

 been observed in both germs. The fragmentation of the 

 cells into rod-, or coccus-like forms is analogous to that of 

 the true streptothrix. The club-shaped rods are involution 

 forms similar to those observed in actinomyces. More- 

 over, the necrotic action or the production of new growths 

 by these bacilli differs in no wise pathologically from sim- 

 ilar changes induced by the true streptothrix. 



Under the term streptothrix are to be classed: the 

 fungus of lumpy- jaw, of which there are perhaps several 

 species; that of farcy in cattle, and that of Madura-foot 

 in man. Moreover, many forms of pseudo-tuberculosis in 



