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. 
