ACTINOMYCES 269 



each granule is found to consist of one or many rosettes of club- 

 shaped organisms arranged in the definite radial manner which 

 suggested their name. Each rosette is composed of threads which 

 radiate from a center and terminate in glistening club-like endings 

 closely packed together (Fig. 39). The clubs are especially found 

 in lesions where the tissue appears to be displaying a degree of 

 resistance to the growth of the parasite. Consequently they have 

 been thought to represent a means of defense on the part of the 

 parasites against the action of the phagocytes. Other observers 

 have considered them degenerative portions caused by contact 

 with the body fluids. The central threads show true branching 

 and in the older colonies a tendency to segmentation which gives 

 to them the appearance of a chain of cocci. It has been sug- 

 gested that the coccus-like bodies may be spores or conidia. The 

 view, however, is not generally held. The threads stain readily 

 with the anilin dyes and are Gram positive, while the clubbed 

 ends lose the color and take on the counter-stain. 



Cultivation. The organism is regarded by most authorities 

 as a strict anaerobe. On agar or glycerin agar at 37 C. growth 

 is visible after several days as small yellowish points which after 

 becoming confluent resemble somewhat a culture of tubercle bacilli. 

 The organisms penetrate into the medium, making the growth 

 difficult to remove ; in broth a sediment is deposited at the bottom 

 of the tube in the form of solid white granules. In order to obtain 

 a pure culture the following method has been recommended: 

 granules are removed from a lesion, thoroughly washed in sterile 

 water to remove extraneous organisms, and then crushed between 

 two sterile coverslips. A microscopic examination is made to be 

 sure a filamentous mass is present ; otherwise, especially in bovine 

 material, no development will take place. If filaments are seen 

 a portion of the crushed granule is transferred with a platinum 

 loop to tubes of melted 1 per cent glucose agar cooled to 40 C. 

 and thoroughly distributed through the medium. At the same 

 time a number of the granules after washing are placed on the side 

 of a sterile test tube and allowed to dry at room temperature in 

 the dark. In this way all contaminating organisms will be killed 



