CHAPTER XII. 



ACTINOMYCOSIS AND ALLIED DISEASES. 



ACTINOMYCOSIS is the most important example of a group of 

 diseases produced by streptothrix organisms. It is related, by 

 the characters of the pathological changes, to the diseases which 

 have been described. The disease affects man in common with 

 certain of the domestic animals, though it is more frequent in 

 the latter, especially in oxen, swine, and horses. The parasite 

 was first discovered in the ox by Bol linger, and described by 

 him in 1877, the name actinomyces or ray fungus being from its 

 appearance applied to it by the botanist Harz. In 1878 Israel 

 described the parasite in the human subject, and in the following 

 year Ponfick identified it as being the same as that found in the 

 ox. Since that time a large number of cases have been observed 

 in the human subject, the result of investigation being to show- 

 that it affects man much more frequently than was formerly 

 supposed. 



It is, however, to be noted that the term " actinomyces," as 

 originally used, does not represent one parasite but a number of 

 closely allied species, as cultures obtained from various sources 

 have presented considerable differences ; and, further, it is noted 

 that other distinct species of streptothrix have been cultivated 

 from isolated cases of disease in the human subject where the 

 lesions resembled more or less closely those of actinomycosis. 

 In one or two instances the organism has been found to be 

 "acid-fast," and there is no doubt that the actinomyces group is 

 closely related through intermediate forms with the tubercle 

 group (vide p. 239). 



Naked-eye Characters of the Parasite. The actinomyces 

 grows in the tissues in the form of little round masses or colonies, 

 which, when fully developed, are easily visible to the naked eye, 

 the largest being about the size of a small pin's head, whilst all 

 sizes below this may be found. When suppuration is present, 



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