3 G6 BA CTERIOL OGY. 



More or less imperfectly studied varieties of actino- 

 mycetes have been encountered in abscess of the brain, 

 cerebrospinal meningitis, endocarditis, bronchopneumo- 

 nia, pleuropneumouia, pustular exanthemata, abscess of 

 the lung, bronchiectasis, pulmonary gangrene, necrosis 

 of the vertebrae, subphrenic abscess, noma, and pseudo- 

 tuberculosis. 



In some cases the actinomycetes can be obtained in 

 culture from the diseased tissues ; almost as often they 

 cannot. Sometimes the inoculation of animals with 

 bits of the diseased tissue or with cultures results in the 

 production of pathological lesions referable to the organ- 

 ism ; again, no eifect follows upon such inoculation. As 

 seen in the tissues by microscopic examination, actino- 

 mycetes may appear as long, convoluted, irregularly stain- 

 ing, beaded, branching threads, or as clumps of short, 

 markedly beaded, sometimes branched rods. At times 

 a clump of the short or longer threads is encountered 

 in the tissues that gives the distinct impression of 

 mycelial structure. 



Some of the varieties that have been described are 

 best demonstrated in the tissues or exudates by the 

 Gram or Gram-Weigert method of staining ; others are 

 decolorized by this process, and are rendered visible 

 only by the simpler procedures. Some of them are to 

 a limited extent proof against the action of acid decolor- 

 izers. Though many accounts of the presence of these 

 morphological types in a variety of conditions have 

 been recorded, the descriptions in the main are meagre 

 and often insufficient for identification. A few, how- 

 ever, have been found so constantly in association with 

 more or less definite clinical and pathological conditions 

 that a brief description of them may be of service. 



