ACTINOMYCOSIS. 211 



When the actinomyces are grown upon artificial media 

 their virulence is retained for a considerable length of 

 time. If introduced into the abdominal cavities of rab- 

 bits, 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 egg the organism 

 forms peculiar long mycelial threads quite unlike 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. 



