CHAPTER XIII 



COLOUR PHOTOMICROGRAPHY 



THE possibilities of an exact reproduction of the appear- 

 ance of a microscopic object have been immensely in- 

 creased by the application of colour photography to 

 photomicrography. A monochrome rendering of the 

 majority of preparations is quite adequate for most 

 purposes, but the great use made of staining processes 

 and the advantages offered by these as a means of 

 differentiation, owing to the selective action of both 

 animal and vegetable tissues for various stains, are suffi- 

 cient to call attention to the desirability of sometimes 

 photographing the object in its actual colours ; and black- 

 and-white prints of naturally coloured objects can never 

 be quite so satisfactory as pictures in which the original 

 colours are faithfully reproduced. 



The colour processes at present most in use result in 

 the production of transparencies, which, however satis- 

 factory for hand examination or projection, are incon- 

 venient for storage. Efforts are being made with a 

 considerable amount of success to perfect methods of 

 reproduction on paper analogous to ordinary printing 

 processes, but so far they are not of great use for photo- 

 micrography. Loss of detail is particularly noticeable 

 in many of the prints so made, and any method, to be 

 suitable for photomicrography, must give prints equalling 

 in detail the original negative or transparency. 



Reproductions of transparencies made by the Auto- 

 chrome, Dufay, Paget, and Three-Colour processes are 



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