ACTINOMYCOSIS. 201 
they may heal, as in tuberculosis, without leaving apparent marks. Ac- 
tinomycites ordinarily spread slowly, little by little, through the blood ves- 
sels, and apparently most 
often through the veins. 
All tissues and all organs 
may be attacked, and if, 
ordinarily, secondary tum- 
ors develop in the lungs, 
they are also observed in 
the liver, kidneys, spleen, 
serous membranes, lympha- 
tic glands, and even the 
encephalon. 
Locally, the disease pro- 
gresses both by continuity 
and contiguity of tissues. 
For instance, pulmonary 
actinomycosis “not only 
generalizes often in both 
lungs, but it extends from 
the visceral layer to the 
parietal layer of the pleura, 
obliterates the pleural cavi- 
ty, and reaches the thoracic 
walls, where its clinical 
signs can be easily recogn- 
ized. 
The ways by which the 
actinomycites are  intro- 
duced are numerous. 
Generally, they penetrate 
through tegumentary so- 
lutions of continuity, 
wounds of the skin, or 
mucous membranes, but 
especially by the wounds 
of the mouth and of the 
pharynx; at times they 
enter through natural pass- 
ages, glandular canals and 
Fig. 49. Actinomycosis of the Tongue. 
orifices of the teats; it is the exception for the disease to start in the 
intestines or the lungs. Pulmonary infection may take place from the 
dust blowing out of forage that contains actinemycites, 
