298 PEACTICAL PHOTO-MICKOGKAPHY 



Stain, Gram and eosin. 



Objective, y^-inch oil-immersion, by C. Keichert. 



Ocular, none. 



Illuminant, mercury- vapour lamp." 



Condenser, Swift achromatic. 



No auxiliary condenser. 



Screen, acid-green and tartrazine. 



Plate, Barnet orthochromatic. 



Exposure, 45 seconds. 



Development, pyro-soda. 



PLATE VII, FIG. 2. Spirochaete pallida. x 1500. 



Staining by Gemse's method. 



Objective, 3-mm. apochromat, N.A. 1*40, by Zeiss* 



Ocular-projection, No. 2. 



Illuminant, arc lamp, taking 4 amperes. 



Condenser, Leitz oil-immersion, used dry. 



Auxiliary condenser, Zeiss No. I. 



Screen, saturated solution of auramine. 



Plate, Wellington orthochromatic process. 



Exposure, 65 seconds. 



Development, metol-hydrokinone. 



This preparation was extremely faintly stained, and it was 

 therefore difficult to get sufficient contrast in the photograph. 

 It is one of a class in which the negative might usefully be 

 intensified by one of the methods described on p. 235, although 

 the figure reproduced has not been so dealt with. 



PLATE VII, FIG. 3. Streptococcus pyogenes. X 1250, 



Cover-glass preparation from pure culture. 



Stain, methyl- violet. 



Objective, -^inch achromatic, by C. Baker. 



Ocular, none. 



Illuminant, electric arc, taking 4 amperes. 



Condenser, Zeiss-Abbe chromatic. 



Auxiliary condenser, Nelson aplanatic bull's-eye. 



Screen, aqueous solution of naphthol-green. 



Plate, Wellington process, orthochromatic. 



Exposure, 6 seconds. 



Development, pyro-soda. 



