1892.] THE MICROSCOPE. 99 



ble with photographic illustrations, in which the shadows in the 

 preparation form the picture itself, and in which, as it were, the 

 microscopical object copies itself. It is therefore impossible to 

 introduce the slightest improvement into the picture except through 

 retouching. 



The necessity of good specimens is apparent. If one publishes 

 a photograph he frees himself from every subjective influence in 

 representing his specimens, and places, to a certain extent, the 

 result of his researches before his critics. He admits them to take 

 a direct share in his observation, and the consciousness that the 

 photograph of the result of his work will expose him to much 

 wider criticism by the scientific world compels a microscopical 

 worker to check the accuracy of his observations and to defer the 

 publication of the result until he is certain of his facts. The gen- 

 eral adoption of photography in micro work would, no doubt, 

 prevent many immature publications. 



The value of photography may be shown by its use in the va- 

 rious questions regarding infective diseases. Koch and Lewis'^ 

 came to an understanding regarding the differences which are 

 found in spirillum of relapsing fever through the publication of 

 their respective photographs. Lewis examined Koch's photo- 

 graphs in Cohn's Beitrd^e, and came to the conclusion that the 

 spirillum of Indian relapsing fever was thicker than the European^ 

 organism. We should have had reported two different spirilla 

 and, as Lewis pointed out, two kinds of relapsing fever produced 

 by them but for publication of the Indian organism. In Lewis's 

 photos the spirilla and blood corpuscles are surrounded by diffrac- 

 tion lines, an infallible sign that, compared with the amount 

 of light, he had used too small a diaphragm hole in his work, and 

 probably also in measuring the object. (Koch.) It is known that 

 the narrower the diaphragm the broader and darker does the 

 edge of the object appear, and if the light is intense, as where 

 sunlight is used, the edge of the object will appear broad and dark 

 from the number of surrounding diffraction lines. It is also well 

 known that stained bacteria should not be illuminated, if the best 

 results are desired, by a very wide opening and not by a narrow 

 hole, but by diffused^ light, by means of which full advantage is 

 taken of the effect of the stain and a perfectly sharp contour ob- 

 tained. This at once shows how easily mistakes would have been 

 overlooked if only the drawings had been made or possibly never 

 seen at all. Koch has photographed specimens of this disease 

 sent by Dr. Carter, of Bombay, and has proved it to be identical 

 with the European. 



Koch says : '' Photography proved of great value in the descrip- 

 tion of Letzerich's plasma corpuscles, plasma balls, swarming 

 with micrococci, etc., illustrating his work on the morphological 



*The microscopic organisms found in the blood of man and animals. Calcutta, 1879. 



