VI COLOUR IN NATURE 



The literature of the subject is so extensive that it 

 has been found impossible within the assigned limits 

 of space to attempt a complete bibliography. I 

 have therefore thought it most advisable to confine 

 myself as far as possible in the list of references 

 to papers actually consulted and discussed in the 

 text. Even thus abbreviated, the list will, I trust, 

 be of value to the workers in the subject. 



I have to express my sincere obligations to Mr. 

 J. A. Thomson for much kind assistance, especially 

 with the literature. 



College of Medicine for Women, 

 Edinburgh, September 1898. 



