Photomicrography 203 



description if it is evident that tlic investioator had presentable 

 preparations. In iUnstrating some materials the very act of making 

 an ink drawing on paper exaggerates magnitude, visibility of details, 

 and texture. For instance, protoplasm does not consist of discrete 

 dots and sharp lines. A photomicrograph accompanied by an inter- 

 pretation drawing affords much more convincing illustrations of 

 many subjects than does either method alone. 



The making of record photomicrographs is often an essential part 

 of diagnostic routine in clinical, chemical, criminological, and many 

 other studies. Under standardized conditions, especially if there is 

 some uniformity in the character of the subjects, such photomicro- 

 graphs can be made by a well-trained technician. 



In some fields of research it is desirable to make photomicrographs 

 of specialized subjects. The investigator is the only one who can 

 locate and recognize the structure under the microscope. He must 

 determine the proper focal level, the correct magnification, color 

 filters, and other factors. The exposure time of the first trial may 

 be a vague guess. The negative must then be developed at once, and 

 the exj^osure time corrected. It may be necessary to make several 

 negatives at different foci in the same field of view. After a correctly 

 exposed negative is obtained, the investigator must personally decide 

 from a contact print whether the photograph shows the desired 

 structures. Research photomicrography of this type is clearly an in- 

 separable part of the research and must be done by the investigator 

 in person, with his research microscope and frequently without dis- 

 turbing the slide that has been under scrutiny. 



It is a common fallacy that a photomicrographer must be primarily 

 a photographer, who can easily and quickly "pick up" what he needs to 

 know about the microscope. On the contrary, he must be a skilled and 

 critical microscopist, furthermore he must be familiar with the struc- 

 ture of the material that is to be photographed. He can learn the pro- 

 cessing of negatives much quicker than he can gain a mastery of micro- 

 scopy. Given a good negative and some supervision by the scientist, 

 the commercial photographer can make excellent contact prints and 

 enlargements. 



This chapter was written for the research worker or teacher who 

 has modest facilities for making photomicrographs and wishes to 

 utilize them to the best advantage. It will be assumed that the ad- 

 vanced worker who has more elaborate facilities has studied both 

 photography and microscopy beyond the elementary scope of this 

 manual. 



