376 VETERINARY BACTERIOLOGY 



stains readily with the common anilin dyes and is gram-positive. 

 It is not acid-fast. 



Isolation and Culture. The organism is not easily isolated 

 in pure cultures, particularly when it occurs in mixed cultures 

 with pyogenic cocci in the lesions. Wright has described a technic 

 which he found quite uniformly successful. Pus or tissues contain- 

 ing the organism in filamentous rosettes is preferable to that con- 

 taining only the clubbed type, as in the latter degeneration has 

 gone so far that frequently no growth will occur. The granules 

 are washed in sterile water, crushed between sterile slides, and 

 inoculated in varying amounts into tubes of melted 1 per cent, 

 dextrose agar, and incubated at 37. In his experience the 



colonies developed character- 

 istically from 5 to 12 mm. 



jritfH 



below the surface, but others 

 have found them to form 

 G& quite as well upon the surface 

 of the medium. Isolated col- 

 onies may then be transferred 

 to other media. In bouillon 

 the organism forms distinct. 

 solid, spherical, or mulberry- 

 like masses at the bottom of 

 the tube. Growth is secured 



Fig. m.Actinomycc8 bovis, tissue with difficulty upon the sur- 

 section showing the radial arrangement .. t , . 



and the clubbing of threads (Gunther). face of the m edmm, accord- 

 ing to Wright, but other in- 

 vestigators have not experienced the same difficulty. It forms 

 on agar and glycerin agar colonies, which at first resemble tiny 

 drops of amber; these enlarge, and either remain discrete or 

 coalesce to form a distinctly wrinkled, " lichen-like " membrane, 

 which frequently has a dusty appearance. Gelatin is slowly 

 liquefied. 



Physiology. The organism may be regarded as a facultative 

 aerobe, as growth appears to take place best under anaerobic 

 conditions. The optimum growth temperature is 37. The 

 organism is resistant to desiccation and will live for a long period, 

 probably months, in a dried condition. Gelatin is liquefied. 



