186 PATHOGENIC MICROORGANISMS. 



that they occur as threads which may under careful cultiva- 

 tion become divided into short segments. They do not have 

 a double wall like the moulds, and are not filled with fluid 

 containing granules, and the segments of the filaments have 

 no distinct partition separating one from the other. 



The most thoroughly studied streptothrices are : the Strep- 

 tothrix actinomyces, or ray fungus, the Streptothrix madurce, 

 and the Streptothrix Eppingeri, all of which have been found 

 associated with important pathological lesions and are be- 

 lieved to be the cause of special diseases. The bacteria of 

 tuberculosis and diphtheria are believed by some to belong to 

 the class of streptothrices, because at times they show a tendency 

 to form branched segments. This view, however, is not generally 

 accepted. It is interesting to note that the lesions caused by the 

 streptothrix have very much the appearance of tuberculous 

 lesions, being almost indistinguishable from tuberculosis except 

 for the absence of the Bacillus tuberculosis. 



In diseases attributable to these fungi, microscopical exam- 

 inations of the tissues reveal the streptothrices in the tissues, 

 and these have been cultivated artificially, and by inocula- 

 tions into animals have reproduced lesions identical with those 

 of the original disease. 



The most important of the diseases caused by one of the 

 streptothrices, and the only one which will be studied in this 

 volume, is : 



ACTINOMYCOSIS. 



Streptothrix Actinomyces (Ray Fungus). 



History. It was described first by Bellinger, in 1877, and 

 found in the disease of cattle known as big-jaw or wooden- 

 tongue, and contained in the tissues and exndates. In man 

 the disease first described by Israel, in 1885, seems to be iden- 

 tical with this cattle disease. 



Morphology. In pus from the affected parts are small yel- 

 lowish granular masses from 2 to 5 millimeters in diameter. 

 Under the microscope these granules are seen to consist of a 

 number of threads which radiate from a centre to a bulbous, 



