$ THE A B C OF PHOTO - MICROGRAPHY 



following descriptions will show the method 

 pursued in making each one and may serve as 

 guides in similar cases. They were all made 

 with the E. R. & C. camera (Fig. 3) by light 

 reflected from a western sky. 



Fig. 23. Corisa undulata, or Water Boatman. 

 This is a large insect of too great size to be 

 comprised within the field of any ordinary 

 microscope objective, but easily shown in that 

 of a photographic lens, which in the present 

 case is one of Beck's rapid rectilinears of 7 

 inches focus, the stop being //22. Plate, 

 Forbes' orthochromatic L; screens two, picric 

 acid and acid-green; exposure, 80 seconds; 

 developer, eiko- hydro; amplification, 3% 

 diameters. 



Fig. 24. Transverse section, stem of Ser- 

 janla^ a tropical climbing plant. This speci- 

 men was quite within the capacity of a 3-inch 

 microscope objective, but was taken with a 

 photographic lens to show the capability of the 

 latter in delineating microscopic details of the 

 cell structure. Lens was Beck's 5-inch recti- 

 linear of same series as that used in the pre- 

 ceding example, with same stop, //22 ; Forbes' 

 orthochromatic plate, L; napthol yellow screen, 

 exposure, 5 minutes ; amplification, 5 diam- 

 eters. 



