ACTINOMYCOSIS. 435 



considerably in size, the appearance of an irregular mosaic is thus 

 produced. 



By pressing upon the cover we break up the rosette, and then 

 the clubs are recognised either singly or in pairs, or attached together 

 in the form of wedge or fan-shaped segments. Calcareous material, 

 if present, may readily be demonstrated by the action of acids. It 

 will be found that on the addition of dilute hydrochloric, nitric or 

 acetic acids, the calcareous deposit is dissolved while the clubs are 

 not affected, and even with the addition of the strongest acids the 

 only result will be to dissolve out the calcareous matter and clarify 

 the tufts of the fungus, the form of the clubs being still recognisable. 

 They are not affected by ether or potash, and thus the effects of 

 chemical reagents clearly distinguish them from fat crystals or 

 calcareous particles. By breaking up the growth into small frag- 

 ments, we may readily study the shape of the individual club-like 

 elements. By using high-power objectives, and properly arranging 

 the illumination, various forms will be clearly delineated. In some 

 cases the club will be found to be bifid at the extremity ; in other 

 cases there are lateral offshoots or daughter-clubs. Here and there 

 will be found clubs closely pressed together like a bunch of bananas, 

 and in other cases the broken-off pieces have a palmate form. By 

 teasing out the grains in water, and pressing them apart between 

 the slide and cover-glass, we find that the central portion is com- 

 posed, as a rule, of a structureless core. More rarely there are the 

 delicate filaments which are found in cultures and in the fungus from 

 man. 



If the grains are mounted in glycerine, the appearance of the 

 •organism in the fresh state may be preserved. 



The granules may be stained by picking them out with needles 

 and transferring them to a watch-glass containing alcohol, to which a 

 few drops of concentrated alcoholic solution of eosin have been added. 

 They remain in the solution until distinctly stained, and they are 

 then placed on a glass slide in a drop of glycerine. 



The muco-pus may be spread out into as thin a film as possible 

 on a cover-glass, allowed to dry, fixed by warming slightly over 

 the flame, and stained by the method of Plaut or of Gram. The 

 characters of the fungus can be so readily recognised in the perfectly 

 fresh state, that methods of staining are of secondary importance 

 in diagnosis, though there are certain minute points which can only 

 be satisfactorily determined by means of suitable dyes. 



