ACTINOMYCOSIS. 6^7 



animals. Nevertheless, the persistence of the disease in certain byres 

 would seem to support the view of direct infection. 



On the other hand, it is proved that the actinomyces is a parasite 

 affecting vegetables, principally the graminaceae, and that domestic 

 animals are most commonly infected through injuries caused by vege- 

 table substances. This is suggested by the discovery of the debris 

 of grain at the point where the lesions have originated. 



Inoculation is commonest in the mouth and on the surface of the 



'^. 



Fig. 273. — Actinomycosis of uiaunuaiy gland (cow), showing growth 

 invading lobules. (Figs. 272 and 273 are from blocks kindly 

 supplied by Mr Gilruth, F.E.C.V.S.). 



tongue, parts which are, so to speak, permanently excoriated. The 

 shedding of the temporary molars favours such accidents, and this is 

 why actinomycosis of the jaw is, relatively, so common. The incisor 

 region may also be inoculated during the shedding of the milk teeth, 

 but as the infected food comes more closely and for much longer 

 periods in contact with the molars, it is easy to understand why 

 actinomycosis is rarer in the incisor region. 



The conditions are less favourable for inoculation of the pharynx, 

 because food does not remain in position there for more than a 



