THE HIGHER BACTERIA 



625 



the presence of filaments. If these are present in reasonable abundance, 

 the material is distributed in tubes of glucose agar, which are then 

 allowed to solidify. If these first cultivations show a large number of 

 contaminations, Wright recommends the preservation of other washed 

 granules in test tubes for several weeks, in the hope that contaminating 

 microorganisms may thus be killed by drying 

 before the actinomyces lose their viability. 



If cultivation is successful colonies will ap- 

 pear, after two to four days at 37.5° C, as minute 

 white specks, which, in Wright's cultures, ap- 

 peared most abundantly within a zone situated 

 5 to 10 millimeters below the surface of the 

 medium, Above and below this zone they are 

 less numerous, indicating that a small amount of 

 oxygen furnishes the best cultural environment. 

 Upon the surface of agar slants, growth, if it 

 takes place at aU, is not luxuriant. 



In alkaline meat-infusion broth growth 

 takes place in the form of heavy, flocculent 

 masses which appear at the bottom of the tubes. 

 Surface growth and clouding do not take place. 



Milk and potato have been used as culture 

 media but are not particularly favorable. 



Pathogenicity. — As stated above, actinomy- 

 cosis occurs spontaneously most frequently 

 among cattle and human beings. It may also 

 occur in sheep, dogs, cats, and horses. Its loca- 

 tions of predilection are the various parts 

 adjacent to the mouth and pharynx. It occurs 

 also, however, in the lungs, in the intestinal 

 canal, and upon the skin. When occurring in 

 its most frequent location, the lower jaw, the 

 disease presents, at first, a hard nodular swell- 

 ing which later becomes soft because of central necrosis. It often 

 involves the bone, causing a rarefying osteitis. As the swellings 

 break down, sinuses are formed from which the granular pus is 

 discharged. The neighboring lymph nodes show painless, hard swell- 

 ings. Histologically, about the filamentous knobs or granules, there is a 

 formation of epithelioid cells and a small round-cell infiltration. In 

 older cases there may be an encapsulation in connective tissue and a 

 41 



Fig. 142. — Actino- 

 myces Granule 

 Crushed Beneath a 

 Cover-glass. U n - 

 stained. The prepara- 

 tion shows the margin 

 of the granule and the 

 "clubs." (After Wright 

 and Brown.) 



