258 ACTINOMYCOSIS 
mals. Johne, Piana, Bostroem and others have found it on the awns 
of grain which were imbedded in the tonsils of pigs and in the tongues 
of cattle. Mayo, after making a careful study of this disease, states 
that the actinomyces are probably a degenerative form of some fungus 
which grows naturally upon food stuffs or grain. Bostroem enter- 
tains the view that they develop exclusively on grains, particularly on 
the awns of barley. 
The period of incubation is not known. 
— 
Infection. While actinomycosis is an infectious disease it does not 
seem to be transmitted directly from one animal to another. Numer- 
ous investigators have tried to produce it by inoculating cattle, calves, 
sheep, goats, pigs, dogs, cats, rabbits and guinea pigs with actinomyco- 
tic lesions. The results have almost invariably been negative when 
pus was used, but the disease has developed after inoculating cattle 
with pieces of tissue containing the organism in its vegetating state. 
The supposition is that the parasite gains entrance to the living 
tissues through slight wounds of the mucous membrane of the mouth 
or throat and perhaps the alveoli of diseased teeth or during the shed- 
