334 BACTERIOLOGY. 



There is also reason for believing that there are 

 different forms of actinomycosis in animals, and that 

 the rare disease in man differs etiologically from the 

 not so uncommon disease in cattle. It is only then pro- 

 visionally that the different forms are here, described 

 under one heading. 



Actinomyces. Actinomycosis is a disease 

 occurring in animals * and occasionally in man.f 

 It is caused by a parasite known as Actinomyces, 

 or the " ray-fungus." The parasite appears in the 

 form of a rosette of pyriform or club-shaped ele- 

 ments (Plate XXTX., Fig. i). The little masses are 

 colourless, pure white, or of a yellowish or yellowish- 

 green tinge, and visible to the naked eye. 



The fungus is believed to effect an entrance to 

 the animal by the mouth, being taften in with the 

 food, possibly through the medium of a wound of 

 the gum or a carious tooth. In whatever manner 

 it has gained access to the living organism, it sets 

 up inflammation in its neighbourhood, resulting 

 in the formation of a neoplasm, composed chiefly 

 of round cells, resembling a tuberculous nodule. 

 The nodules may break down and suppurate, or 

 may go on increasing in size. Fibrous tissue develops 

 between the nodules, and large tumours eventually 

 result containing purulent cavities and excavations. 



* Bellinger, Centralbl. f. Med. Wiss. 1877. 



t Israel, Virchow' s Archiv, vols. 74 78. Pontick, Die Actino- 

 mycose des Menschen. 1882 ; and Beitr. z. Kenntn. der Actino- 

 mycose des Menschen. 1882; Lancet, May 2nd, 1885 ; Conti, Gaz. 

 Med. Hal. Lombordia, 1885 ; Acland, Trans. Path. Soc. 1886. 



