1 84 PHOTO-MICROGRAPHY. [CH VIII. 



Thus among the very first of the experiments in photography the microscope 

 was called into requisition. And naturally, plants and motionless objects were 

 photographed in the beginnings of photography when the time of exposure re- 

 quired was very great. 



At the present time photography is used to au almost inconceivable degree in all 

 the arts and sciences and in pure art. Even astronomy finds it of the greatest 

 assistance. 



Although first in the field, Photo-Micrography has been least successful of the 

 branches of photography. This is due to several causes. In the first place, mi- 

 croscopic objectives have been naturally constructed to give the clearest image to 

 the eye, that is the visual image as it is sometimes called, is for microscopic obser- 

 vation, of prime importance. The actinic or photographic image, on the other 

 hand, is of prime importance for photography. Then for the majority of micro- 

 scopic objects transmitted light (§ 50) must be used, not reflected light as in ordin- 

 ary vision. Finally, from the shortness of focus and the smallness of the lenses, 

 the proper illumination of the object is accomplished with some difficulty, and the 

 fact of the lack of sharpness over the whole field with any but the lower powers, 

 have all combined to make photo-micrography less successful than ordinary 

 macro-photography. So tireless, however, have been the efforts of those who be- 

 lieved in the ultimate success of photo-micrography, that now the ordinary achro- 

 matic objectives and ortho chromatic or isochromatic plates give very good results, 

 while the apochromatic objectives with projection oculars give excellent results, 

 even in hands not especially skilled. The problem of illumination has also 

 been solved by the construction of achromatic and apochromatic condensers and 

 by the electric and other powerful lights now available. There still remains the 

 the difficulty of transmitted light and of so preparing the object that structural de- 

 tails shall stand out with sufficient clearness to make a picture which shall 

 approach in definiteness the drawing of a skilled artist. 



The writer would advise all who wish to undertake photo-micrography seriously, 

 to study samples of the best work that has been produced. Among those who 

 showed the possibilities of photo-micrographs was Col. Woodward of the U. S. 

 Army Medical Museum. The photo-micrographs made by him and exhibited at 

 the Centennial Celebration at Philadelphia in 1876, serve still as models, and no 

 one could do better than to study them and try to equal them in clearness and 

 general excellence. According to the writer's observation 110 photo-micrographs 

 of histological objects have ever exceeded those made by Woodward, and most of 

 them are vastly inferior. It is gratifying to state, however, that at the present 

 time (1S96) many original papers are partly or wholly illustrated by photo-micro- 

 graphs, and no country has produced works with photo-micrographic illustrations 

 superior to those in "Wilson's Atlas of Fertilization and Karyokinesis " and 

 " Starr's Atlas of Nerve Cells," issued by the Columbia University Press. 



briefly recapitulate, photography is apparently somewhat indebted to microscopy 

 for the first fleeting pictures of Wedgwood and Davy [1802], the first methods of 

 producing permanent paper prints [Reede, 1S37-1839], the first offering of prints 

 for sale, the first plates engraved after photographs for the purpose of book illustra- 

 tion [Donne & Foucault, 1845], the photographic use of collodion [Archer & Dia- 

 mond, 1851], and finally, wholly indebted for the origin of the gelatino-bromide 

 process, greatest achievement of them all [Dr. R. L. Maddox, 187]]. See further 

 for the history of Photo-micrography, Neuhauss, also Bousfield. 



