THE A B C OF PHOTO MICROGRAPHY 



by a dirty or imperfect background highly 

 magnified on the screen, and the utmost care 

 should be taken to avoid this, not only in 

 making both negative and positive, but also 

 in the preparation of the object to be photo- 

 graphed. The mounting should be abso- 

 lutely clean and free from specks of any 

 foreign substance. No subsequent careful- 

 ness in the photographic manipulations can 

 entirely compensate for defects in a faulty 

 microscopic preparation. 



Two illustrations, representing the front 

 and back of a lantern slide prepared in ac- 

 cordance with the foregoing directions, are 

 given. They are of the standard American 

 size 3/^x4 inches. Fig. 27 is a transverse 

 section of a compound ovary, magnified 20 

 diameters, and occupies the center of the cut- 

 out, with clear glass about it. Fig. 28, the 

 compound eyes of a water-beetle (Dytiscus 

 Marginalis), +75, fills the entire circle. Each 

 oil these facets or eyes being a convex lens, 

 shows an image of the radiant used in mak- 

 ing the negative. Both slides were printed by 

 contact, as with a paper print. 



