﻿Explanation 
  of 
  Plate 
  V. 
  

  

  A. 
  Photograph 
  of 
  asters 
  so 
  screened 
  as 
  to 
  give 
  the 
  relative 
  

  

  luminosity 
  values. 
  

  

  B. 
  Ditto 
  when 
  only 
  yellow 
  green 
  rays 
  are 
  used, 
  the 
  plate 
  being 
  

  

  thus 
  red-blue 
  blind. 
  

  

  C. 
  Ditto 
  when 
  red 
  and 
  part 
  of 
  green 
  rays 
  are 
  used, 
  plate 
  blue- 
  

  

  bhnd. 
  

  

  D. 
  Ditto 
  with 
  red 
  rays 
  eliminated, 
  plate 
  red-blind. 
  

  

  