;8 CLINICAL BACTERIOLOGY AND H^MATOLOGY 



removed at a post-mortem examination, should have their cut 

 surfaces rubbed upon the surface of a slide, and the film thus 

 obtained treated in a similar way ; or they may be scraped, and 

 the scrapings spread on a slide. Sections may also be cut, 

 but are not usually necessary for the diagnosis. 



EXAMINATION OF THE SPECIMENS. 



Actinomycosis of cattle is caused by the ray fungus, an 

 organism which derives its name from the star-shaped 

 colonies which it forms whilst growing in the tissues. It con- 

 sists of two chief parts; the central portion of the colony is 

 formed of a network of narrow filaments, which have radial 

 arrangement at the periphery (Plate II., Fig. 6). In this part 

 small bodies which have the appearance of cocci may often be 

 seen. The outer zone consists of the clubs which (when 

 present) are so characteristic. These clubs are flask-shaped 

 expansions of the sheath of the radial filaments already men- 

 tioned and are arranged with their narrow extremities point- 

 ing inwards. They are not generally present in man, and 

 when present are often badly developed ; they are much more 

 common and more perfect in the ox, where the disease is more 

 chronic and pus-formation rare. (They may sometimes be 

 seen in wet unstained preparations from human cases when 

 they cannot be detected in stained films.) 



The reason for this is, perhaps, partly that man is less 

 resistant against the organism, but probably the chief factor 

 is the difference in the fungus present. The organism in 

 bovine actinomycosis is the ray fungus, which is described 

 above; but in man there are numerous species of fungus which 

 can bring about infection and cause the disease known 

 clinically as actinomycosis : this disease is therefore not a 

 specific entity, due to a single cause, but a group of allied 

 diseases, just as suppuration is. The organisms in question 

 are all members of the genus Streptothrix, and consist of long- 

 filaments of mycelium, which differ from the bacteria in show- 

 ing true branching and in breaking up into "chain spores," 

 resembling chains of cocci. The different species vary very 

 greatly in cultural characters, but there are also marked differ- 

 ences in the appearances met with in films of pus, etc. In 

 what may be regarded as typical cases, the nodules described 

 above, when flattened out and stained by Gram's method, 



