THE STUDY OF INSECT LIFE 31 



given a really good lens ; and the image on the 

 ground-glass focussing screen critically focussed, 

 the resulting negative should be capable of 

 yielding perfectly crisp and sharp enlargements, 

 up to almost any size. Each negative should be 

 carefully indexed, and a note-book kept in which 

 to enter the subject, plate used, exposure, stop, 

 light, and date. 



