X ii LIST OF ILL USTRA TIONS. 



155. Engraving glass (The Bausch & Lomb Opt. Co. ) 19S 



156. Bausch & Lomb's chain lens-holder for use with a dissecting lens, hold- 



ing an engraving glass, etc. (B. &L. ) 199 



157. Bull's eye and lamp (Fig. 52 repeated) 200 



158. Zeiss' vertical photo-micrographic camera (Zeiss' catalog) 202 



159. Rack for drying negatives (Rochester Opt. Co. ) 203 



160-161. Sections of the head and brain of Diemyctylus (Mrs. Gage, from the 



Wilder Quarter Century Book) 203 



162. Vertical photographic camera for picturing brains and other preparations 



in a horizontal position 207 



1^4. Abbe's test plate 211 



165. Abbe's apertometer (Zeiss' catalog) -212 



