36 THE AMERICAN MONTHLY [Jan. 



C Aniline oil, lO.O 



\ Picro-aniline solution, 0.001 



f Aniline oil, 10.0 



\ Eocene- aniline solution, 0.201 



If any part of the preparation acquires too strong a 3'ellow or 

 red color, this may be removed by immersion for half an hour 

 in pure aniline. 



A completely decolorized background facilitates an examina- 

 tion of the micro-organism. If it is desirable to examine a 

 specimen of leucocytes, the staining should be preceded by im- 

 mersion in carmine or hematoxylin solution. If a diffuse 

 counterstain is desired, the specimen should, first of all, be im- 

 mersed in an aqua solution of eocene. The eocene coloration 

 disappears during the violet staining process, but reappears 

 after treatment with picro-aniline or eocene-aniline solution. 



This stain does not work well in crusts thicker than a visit- 

 ing card. Masses thicker than this should be cut in flat sec- 

 tions. Sections are made by placing the air-dried crusts in a 

 block of wood and covering with dilute celloidine. A'''ter fifteen 

 minutes the whole is immersed in six per cent alcohol for 

 fifteen minutes, and is then ready for cutting. The staining is 

 then done without dissolving the celloidine. 



If a leucocyte nucleus stain is first employed, the sections 

 should be immersed for five minutes in Grubler's picro-coch- 

 ineal solution, and then thoroughly rinsed in water to remove 

 the excess of picric acid before employing the bacteria stain. 

 Sections of hair, comedones, warts, hypertrophied skin, and all 

 horny tissues may be examined for micro-organisms by this 

 same method. — Modern Medicine. 



Micro-photographic Drawings. — Unna, the eminent der- 

 matologist of Hamburg, suggested in 1892 a method ot making 

 reproductions of micro-organisms which is much superior to 

 the ordinary methods of either drawing or photography, com- 

 bining the accuracy of the latter with the clearness and com- 

 prehensiveness of the former. The method is as follows : 



From properly stained specimens negatives are made. From 

 these negatives light prints are made in soft paper, upon which 

 it is possible to either draw or paint without further prepara- 

 tion. The photographs thus obtained give only the outlines of 



