360 PATHOGENIC BACTERIA. 



time. The disease cannot usually be successfully inocu- 

 lated into the laboratory experiment animals, as the intro- 

 duced fungus elements seem either to become absorbed 

 or encapsulated by connective tissue and do not grow. 

 If successfully introduced into the abdominal cavities of 

 rabbits, there are produced in the peritoneum, mesentery, 

 and omentum typical nodules containing the actinomyces 

 rays. 



The organism can also be grown in raw eggs, into 

 which it is carefully introduced through a small opening 

 made under aseptic precautions. In the eggs the organism 

 forms peculiar, long, branched mycelial threads quite un- 

 like the short forms developing upon agar-agar. 



The characteristic rosettes which are constantly found 

 in the tissues are never seen in artificial cultures. 



The exact manner by which the organism enters the 

 body is unknown. In some cases it may be by direct 

 inoculation with pus, but there is reason to believe that 

 the organism occurs in nature as a saprophyte, or as 

 an epiphyte upon the hulls of certain grains, especially 

 barley. Woodhead records a case where a primary me- 

 diastinal actinomycosis in the human subject was sup- 

 posed to be traced to perforation of the posterior pharyn- 

 geal wall by a barley spikelet swallowed by the patient. 



Cases of actinomycosis are fortunately of rather rare 

 occurrence in human medicine, and do not always occur in 

 those brought in contact with the lower animals. The 

 fungi may enter the organism through the mouth and 

 pharynx, through the respiratory tract, through the di- 

 gestive tract, or through wounds. 



The invasion has been known to take place at the roots 

 of carious teeth, and is more liable to occur in the lower 

 than in the upper jaw. Israel reported a case in which 

 the primary lesion seemed to occur external to the bone 

 of the lower jaw, as a tumor about the size of a cherry, 

 with an external opening. In two cases of the disease 

 observed by Murphy of Chicago both began with tooth- 

 ache and swelling of the jaw. A few cases of dermal 



