APPARATUS, MATERIAL, AND REAGENTS. I? 



Canada balsam. 

 Dissolved in xylol. 



Glycerine gum (Farrant's solution). 

 Glycerine. 

 Water. 



Saturated solution of arsenious acid. 

 Equal parts, mix and add of picked gum arabic 

 half a part. 



Hollis' glue. 

 Zinc-white. 



(E) DRAWING AND PHOTOGRAPHIC APPARATUS. 



Camera Lucida. The camera lucida of Zeiss 

 is an excellent instrument, though many prefer the 

 pattern made by Nachet of Paris. Combined with 

 the use of a micro- millimeter objective it affords also 

 a simple method for the measurement of bacteria. 



For drawing microscopical appearances, and for 

 illustrating microscopical specimens with or without 

 the use of a camera lucida, the following materials 

 should be within reach : 



Pencils. 

 Etching Pens. 

 Prepared Indian Ink. 

 Water-colour Paints and Brushes. 

 Ordinary and tinted drawing paper and other usual 

 accessories. 



Photo-micrographic Apparatus. Zeiss of 

 Jena, Seibert & Kraft of Wetzlar, Nachet of Paris, 



2 



