RAY FUNGUS. 145 



Form. In the pus or scrapings, little yellow grains about 

 the size of a pin's head are seen by the naked eye. When one of 

 these points is flattened out between the cover-glass and slide 

 and placed under microscope (200 x), aster-shaped figures will 



Kir,. 75. 



Actinomyces. 



be seen, the centre thick, radiating from it, little hyphens, which 

 become thicker and rounder at their peripheral end. These 

 bottle-shaped hyphens are supposed to be the spore-bearing 

 organs. Some of these may have separated from the main body 

 and lie loose or attached to it by a very thin filament. 



Growth. Develops only at brood heat and by exclusion of 

 oxygen. 



In Agar. After several weeks a yellowish growth was ob- 

 tained, but this consisted mainly of mycelia, the club-shaped or 

 conical rays not forming. 



In eggs a growth developed when the method of Hueppe was 

 carried out. 



Pathogenesis. When a portion of the growth obtained in 

 eggs was injected into the abdominal cavity of a rabbit, actinomy- 

 cotic processes developed upon the peritoneum. 



It usually gains access to the living body through a wound in 

 the gum or some caries of the teeth. A new growth is formed, 

 ulceration being first set up. 



The new tissue, composed of round cells, then undergoes soft- 

 10 



