THE ACTINOMYCES 



455 



access to the system through slight scratches or wounds 

 in the mucous membrane of the mouth, pharynx, or larynx. 

 In man no source of infection has been traced, though 

 cases have been reported where the disease has occurred 

 after eating grains of barley, etc. The disease is met with 

 not only in cattle, but also in horses and swine. In the 

 last-named animals considerable calcification may be 



FIG. 50. Actinomyces. Film preparation. 

 Gram. X 750. 



present in the nodules, and it may be necessary to decalcify 

 with dilute nitric or hydrochloric acid before the rosettes 

 can be stained. 



It is important to note that tuberculin may cause a 

 reaction in actinomycosis, similar to that which occurs 

 in tuberculosis, and as the actinomycotic lesions are very 

 like those which are found in the latter disease, mistakes 

 may easily be made, and can only be avoided by a micro- 

 scopical examination. It is of considerable practical 



