INFECTION 207 



Others have found it on the awns of corn which were imbedded 

 in the tonsils of pigs and in the tongues of cattle. Mayo 

 states, after making a careful study of this disease, that the 

 actinomyces are probably a degenerate form of some fungus 

 which grows naturally upon food stuffs or grain. Bostroem 

 entertains the view that they develop exclusiveh' on grain, 

 particularly on the awns of barley. 



§ 164. Infection. While actinomycosis is an infectious 

 disease it does not seem to be transmitted directly from one 

 animal to another. Numerous investigators have tried to pro- 

 duce the disease by inoculating cattle, calves, sheep, goats, 

 pigs, dogs, cats, rabbits and guinea-pigs with actinomycotic 

 lesions. The results have almost invariably been negative 

 when pus was used, but the disease has developed after inocu- 

 lating cattle with pieces of tissue containing the fungus in its 

 vegetating state. 



It is believed that the infection occurs in susceptible 

 species by the introduction of the fungus on food stuffs. 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 shedding of the milk teeth. It multiplies and ex- 

 tends from the points of entrance. After the infected awns 

 once gain lodgement, especiall}' between the teeth, they are 

 removed only with difficulty. The favorite points for the act- 

 inomyces to enter the tongue is 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 has been rarel}- observed primarily in the udder but 

 frequently in the subcutaneous tissue about the head. 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 who were not occupied in agricul- 

 tural pursuits or in handling grain but who 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 of this fungus indicates that it 



