CHAPTER XIII. 



ACTINOMYCOSIS AND ALLIED DISEASES. 



Actinomycosis is a disease of special interest, inasmuch as 

 it is the most important example of a microbic affection in which 

 the parasite belongs to the higher order of bacteria. 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 Bollinger, and described by him in 

 1877, the name actinomyces or ray fungus being from its appear- 

 ance applied to it by the botanist Harz. In 1878 Israel de- 

 scribed 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, very probable that the term actinomyces does 

 not represent one parasite but a number of closely allied spe- 

 cies, as cultures obtained from various sources have presented 

 considerable differences. It is also to be noted that other dis- 

 tinct species of streptothrix ^ have been cultivated from isolated 

 cases of disease in the human subject where the lesions resem- 

 bled 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. 240). 



Naked-eye Characters of the Parasite. — The actinomyces 

 grows in the tissues in the form of little round masses or colo- 

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



^ See footnote to p. 1 6. 

 287 



