648 Actinomycosis. 



that the cause of actinomycosis of -man and animals is an obligatory 

 parasite which will not grow at room temperature and exists as a per- 

 manent inhabitant of the digestive tract from which it occasionally 

 penetrates the underlying tissues. Foreign bodies, according to the 

 latter 's view, play a part in this process only in so far as they assist 

 the parasite in gaining an entrance into the tissue substance. According 

 to Wright the saprophytic fungi that are found on grains, etc., should 

 be differentiated from the true actinomyces as belonging to the group 

 "Nocardia." 



Infection is favored on the other hand by the soft and 

 swollen condition of the mucous membranes of the mouth and 

 gums or by injuries such as occur during the shedding of 

 the teeth (Roger, Imminger, Schouten), or in the course of 

 foot and mouth disease (Paletti). On the other hand infection 

 is favored by the anatomical structure of the tongue. The 

 remarkable frequency of actinomycosis of the tongue in mature 

 cattle bears a certain relationship to the fact that the forma- 

 tion of the so called "groove" of the tongue begins at that 

 time as a result of atrophy of the filiform papillae on the cres- 

 cent-shaped surface of the tongue, causing the mucous mem- 

 brane to become thinner and drawn into transverse folds. Hard 

 particles of food become lodged in this groove and are, by the 

 muscular contraction of the tongue, forced into its interior 

 (A. Breuer). According to Henschel, Falk and Nicolaus par- 

 ticles of plant food are retained especially in young animals 

 by the horn-like filiform papillae, and are tluis afforded a 

 favorable opportunity for entering the pocket-like depressions 

 which are located just anteriorly to the dorsal prominence of 

 the tongue. In the more posterior portions of the digestive 

 tract this method of infection is not as frequently observed, 

 which is explained by the fact that food particles when they 

 reach these regions have been moistened with the saliva and 

 become softer in consistency. In spite of this fact infection 

 occasionally occurs in the esophagus and even in the intestinal 

 wall, especially in the region of the cecum where the feces 

 are dryer and are retained for a longer time. 



Infection by means of the inhaled air may be assumed in 

 such cases only where the lungs are the primary seat of the 

 disease. 



The skin affords an effective protection and consequently 

 infection is possible only through injuries. Castration wounds 

 in horses, more rarely in cattle and swine, constitute the most 

 frequent ports of entrance for the contagion. So called scirrhus 

 cord is the result at least in a part of the cases of contact 

 Avith infected straw (Johne). The development of actinomyco- 

 mata in other regions of the body as a result of superficial or 

 deeper injuries of the skin are much more rare (Gooch ob- 

 served them in cattle treated with setons, Lienaux after 

 rumenotomy). Finally, this parasite may gain entrance into 



