ACTINOMYCOSIS. 223 



In plate culture the colonies first appear as very small 

 filamentous grayish masses. On blood-serum, gelatin, agar- 

 agar, and glycerin-agar, the growth develops in the form of 

 small yellowish or grayish colonies, which soon coalesce to 

 cover the entire surface of the medium with a thick dry 

 wrinkled fluffy membrane, which adheres to the media very 

 firmly. It is utterly impossible to remove the growth with- 

 out tearing it into shreds. Projecting from the surface 

 growth down into the medium are many fine threads. Blood- 

 serum and gelatin are liquefied. The surface of bouillon is 

 covered by a membrane just like that on the solid media, but 

 the fluid is perfectly clear. Frequent shaking of the flask 

 breaks the membrane into many small granular masses. 



The growth on potato is yellowish-red in color, and is 

 covered by a very fine white fur. The actinomyces grows 

 quite readily in both raw and boiled eggs. It is introduced 

 into the egg through a small opening made with a hot needle. 

 The opening can be sealed with collodion, sealing-wax, or 

 paraffin. Milk is peptonized. In all stab cultures the growth 

 forms on the surface of the medium, and the track of the 

 needle soon becomes filled with a grayish turbid fluid. The 

 cultures are quite resistant to drying. They are killed in five 

 minutes by a temperature of 75 C. 



The many variations of this organism, or what might be 

 called transition-stages, can readily be studied in the cultures. 

 There are long wavy filaments of uniform size ; short, thick 

 rods, either perfectly straight or slightly curved like the 

 tubercle bacillus ; filaments with segmented ends like a spore- 

 containing mycelium in the thrush mould ; many micrococcus- 

 like bodies, branching forms, rods and filaments with club- 

 shaped extremities, all of which must be considered as dis- 

 tinct stages in the development of this remarkable organism. 



Pathogenesis : The disease is common in cattle, and is 

 usually located in the jaw, where it forms a distinct swelling. 

 It is commonly known as lumpy jaw. The actinomyces is 

 ingested with the food (cereals), and then finds its way into 

 the jaw-bone through a carious tooth or an injury or abrasion 

 of the gum. It develops rapidly, forming a granulomatous 

 tumor, somewhat similar to a tubercle, which contains many 



