ACTINOMYCOSIS 259 
ding of the milk teeth. It multiplies and extends from the points of 
entrance. After the infected awns once gain lodgment, especially 
between the teeth, they are removed only with difficulty. The 
favorite points for the actinomyces to enter the tongue are on the upper 
surface midway between the dorsum and the tip. The lungs may be 
the seat of primary infection due to the inhalation of the fungus. 
The disease rarely has been observed primarily in the udder but 
requently in the subcutaneous tissue about the head. 
Fic. 56. HEAD OF A STEER WITH ACTINOMYCOSIS OF THE LOWER JAW. (PHOTOGRAPH 
BY HOPKINS). 
In man the source of infection is more obscure. Many cases have 
been reported where the individuals did not come in contact with 
diseased animals and were not occupied in agricultural pursuits or in 
handling grain but were glaziers, tailors and various shop tenders. 
There are a few cases reported, however, where the circumstantial 
evidence points to direct infection from diseased animals. 
The present knowledge indicates that the organisms must attain 
to a certain stage or period in their development before they will live 
and multiply in living animal tissues. It has been observed that, as a 
tule, cattle become infected when they are kept upon dry food. 
