/7. Photomicrography 



The use of photomicrographs for illustrations in teaching and 

 research has become a firmly estaljlished practice. A choice between 

 drawings and photomicrographs should be based on an understanding 

 of the limitations and possibilities of these methods and upon the 

 method of reproduction to be used. A drawing may be said to ex- 

 pound and explain the subject, while a good photograph is an 

 accurate, impersonal reproduction of the subject. A drawing may 

 be a routine diagrammatic record of rather gross structures, or it 

 may represent the interpretations of the microscopist, either in full 

 detail or in idealized, semidiagrammatic form. The routine type 

 can be made by an artist; the interpretation drawing can be made 

 only by the investigator sitting at his microscope. Photographs have 

 similar characteristics and range from mere routine recording to the 

 most critical probing of structural details. 



Instead of arguing the relative merits of dra^vings and jihoto- 

 graphs, the experienced and versatile worker simply decides which 

 method will best serve a specific need and uses such talent as he has 

 or can hire. A few simple examples will illustrate the criteria by which 

 a choice can be made between methods of scientific illustration. A 

 cross section of a corn stem, or the corn kernel in the frontispiece con- 

 tains several thousand cells. To make a drawing which woidd purport 

 to be an accurate cell-for-cell representation would be an almost in- 

 credibly laborious task (for someone else to do) . A photomicrograph 

 of such subjects reproduces with acceptable accuracy the number, 

 distribution, shapes, and sizes of the numerous cells and, furthermore, 

 reproduces texture in a way that can only be remotely approached 

 by the most talented artist. Photomicrograjihs of this type can be 

 made only by a photographer who is familiar with plant materials. 

 Controversial siil))i(ts or luw and siriking discoveries deserve 

 photographic illustrations. The reader has greater confidence in a 



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