INTRODUCTORY 5 



over by advanced workers in most branches 

 of science. It received its first, and probably 

 greatest advance, through the labors of our 

 own Dr. J. J. Woodward, of the Army Med- 

 ical Museum in Washington, whose fame was 

 and is world-wide. His work in some directions 

 has never been excelled, although it antedated 

 homogeneous and apochromatic objectives, 

 gelatine dry plates and other appliances now 

 so common and thought to be indispensable 

 for high-class work. Dr. Maddox, of Eng- 

 land, recently deceased, gave throughout a 

 notable career of more than half a century, 

 a wonderful amount of help to all workers in 

 photo-micrography. By the aid of the half- 

 tone engraving process, faithful and beautiful 

 reproductions are furnished at a nominal cost, 

 and it may be confidently predicted that here- 

 after no work dealing with any subject requir- 

 ing the aid of a microscope will be published 

 without being copiously illustrated by photo- 

 micrographs, reproduced through the half-tone 

 processes; most likely in trichrometry. 



For many years I have been fully convinced 

 of the importance of photo-micrography in 

 educational interests, 5 and the trend of thought 

 and action in that direction seems to more 

 than justify my opinions. In some of the 



