ETIOLOGY 



30: 



found to be made up of rosettes varying in size from 10 to 

 200// in diameter, the average size ranging from 301040//. 

 This fungus can be cultivated on artificial media. It stains 

 somewhat feebly with the aniline dyes. 



The rosettes are composed of a number of club-shaped 

 structures (rays), radiating from the central mass which is 

 composed of the mycelial part of the fungus. The club-shaped 

 bodies vary in size but usually they are from i to 10// long. 

 The rays are connected with the central portion by fine thread- 

 like structures which are not readily demonstrated. In tear- 

 ing or crushing the rosette, the clubs break off at or near their 

 junction with the mycelial threads. Some investigators have 

 mentioned a polymorphous form of actinomyces in which 

 coccoid and rod-shaped structures are found. These are doubt- 

 less the ends of the clubs which first appear in focusing on a 

 rosette. 



The mycelial threads are wider in some portions than in 

 others. In the narrowest places the walls seem to touch each 

 other. Whether this irregularity is natural or the result of 

 twisting the mycelial thread is not determined. The myce- 

 lium is much more difficult to stain than the clubs. In some 

 cases it seems to branch. The filaments can rarely be seen in 

 the rosettes as they occur in the suppurating lesions. 



The natural habitat of this fungus is said to be on certain 

 plants. According to Brazzola, they vegetate on the grasses, 

 chiefl}' on Hordetivi mui'inum. He discovered quantities of 

 the fungi between the vegetable fibres of barley which were 

 imbedded in the gums of animals. Johne, Plana, Bostroem 

 and others have found it on the awns of corn 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 stuflfs or grain. Bos- 

 troem entertains the view that they develop exclusively on 

 grains, particularly on the awns of barley. 



The period of incubation is not known. 



