18 OLD FLIES IN NEW DRESSES 



Herbert Maxwell, there would certainly 

 have been most excellent grounds for sup- 

 posing that his theory was true ; but this 

 layer is contained in the fish's eye, though 

 it is not the same as in man. If the fish's 

 eye did not contain it, fish would have 

 been totally blind. 



How far this difference in the retina of 

 the fish bears on its sense of colour is, at 

 present, a moot point, though I believe 

 researches are being made in this direc- 

 tion. At present, our knowledge is too 

 limited with regard to it for any definite 

 statement to be made. The probability 

 is, that fish have the power of distin- 

 guishing colour from colour. A proba- 

 bility, however, is not a certainty, though 

 one is more inclined towards it than 

 towards an improbability. 



Even should Sir Herbert Maxwell's 

 theory prove true, in spite of probabilities 

 to the contrary, I do not see that we 

 should have progressed very much further 

 with regard to facilities in imitating the 

 natural fly. We know that the relative 

 values of light and shade in various colours 

 contiguous to each other, is not actually 



