CHAPTER XII. 



ACTINOMYCOSIS. 



AcxiNbMYCOSis is a disease of special interest, inasmuch as 

 it is the most important example of a microbic affection in 

 which the parasite belongs to a higher order, and presents 

 greater complexity of form, than the ordinary bacteria show. 

 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 Bellinger, 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. The disease 

 in man is characterised by chronic suppurative processes, 

 which often extend to internal organs, producing a sort of 

 chronic pyaemia ; the disease in the pig is of somewhat 

 similar nature. In the ox, on the other hand, and also in 

 the horse, the lesions are characterised by an abundant 

 formation of granulation tissue, often resulting in tumour- 

 like masses of considerable size. 



