228 



PHO TO-MICROGRAPHY 



[ CH. V11I 



FIG. 187. Adjustable lens holder. This lens holder will take magnifiers of 

 various sizes, and from its adjustable mechanism is very convenient for dissecting, 

 or for holding a Steinheil and other lenses for illumination ( The Bausch & Lomb 

 Opt. Co.). 



FIG. 1 88. Engraving glass to 

 serve as a condenser and for a dis- 

 secting lens. {Bausch & Lomb Opt. 

 Co.] 



If one examines a series of photo-micrographs the chances are that the greater 

 number will be of diatoms, plant sections or preparations of insects. That is, they 

 are of objects having sharp details and definite outlines, so that contrast and defi- 

 niteness may be readily obtained. Stained microbes also furnish favorable objects 

 when mounted as cover-glass preparations. 



