DIAGNOSIS 



375 



a drop of 10 per cent sodium hydroxide before the cover slip is put 

 in place. Occasionally the granules may be encrusted with lime salts, 

 in which case treatment with dilute acid is necessary to make their 



structure visible. 



The granules vary in color, the smaller ones being rather trans- 

 lucent and indefinite in color, the larger ones yellowish or even brown. 

 Occasionally there is an associated micrococcus which imparts to 

 them a dark, almost black, color. 



The crannies are best observed in a microscopic preparation with 

 the low-power microscope lens. The interior of the granules will not 



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Fig. 135. Photomicrograph of a crushed, unstained granule from actinomycotic 



pus. The dark irregular lines mark the position of the highly refractile clubs 



bordering the lobules of the granule. 



stand out sharply in unstained preparations, but the clubs at the 

 periphery are quite refractile and will appear as irregular lines 

 marking the borders of the lobules (Fig. 135). Such an examination 

 merely proves the presence of a lobulated granule of the parasite. 

 In human cases this will most probably, but not certainly, be Actino- 

 myces. In bovine cases the identity must be proved by further exami- 

 nation. This may be done by making stained smears. To do this 

 the granules are crushed between two slides and then spread in a 

 thin film which is stained with Gram's stain. In actinomycosis 

 branching hyphae or diphtheroid hyphal elements which are Gram- 

 positive or contain Gram-positive material in beads in and on the 

 cells are found. Usually the club structures are disintegrated by such 

 a procedure, but occasionally they may be recognized in the stained 

 smear where they take the counterstain. 



