268 



ACTINOMYCOSIS. 



ducing enlargement and induration, with nodular thickening 

 on the surface the condition known as " woody tongue." 



Source of the Parasite. There is a considerable amount 

 of evidence to show that outside the body the parasite 

 grows on grain, especially on barley. Both in the ox and 

 in the pig the parasite has been found growing around 

 fragments of grain embedded in the tissues. There are 

 besides, in the case of the human subject, a certain number 



" of cases in which 



there was a history 

 of penetration of a 

 mucous surface by a 

 portion of grain, and 

 in a considerable pro- 

 portion of cases the 

 patient has been 

 exposed to infection 

 from this source. The 

 position of the lesions 

 in cattle is also in 

 favour of such a view. 

 The conditions of 

 growth outside the 

 body in a natural con- 

 dition are, however, 

 not known, nor has 

 the parasite been culti- 

 vated from any source 

 outside the body. 



Cultivation (for 

 A B methods of isolation 



FIG. 68. Cultures of the actinomyces on see later )- Tne acti - 



glycerine-agar, of about three weeks' growth ; nomyces can be cul- 



showing the appearances which occur. The tivated Outside the 



growth in A is at places somewhat corrugated . , , , , . 



on the surface. Natural size. body, and the disease 



has been experiment- 

 ally reproduced in animals. It grows on a variety of media, 

 though on all, its rate of growth is somewhat slow. Growth 



