PREFACE 
This little book is an attempt to set forth in 
systematic order the main facts at present known in 
regard to the Pigments and Colours of Plants and 
Animals. Although there are not a few books 
which treat of the external aspects of the Colours of 
organisms, it is a frequent complaint among those 
engaged in actual research that, not only is the 
physiological side of the subject inadequately treated 
in the text-books, but the literature is also scattered 
and difficult of access. It is hoped that the present 
work may both help to supply this deficiency, and 
also appeal to that wider public whose interest in 
the problems of Colour has been aroused by the 
existing general books on the subject. The popu¬ 
larity of many of these is deservedly so wide, that I 
have endeavoured throughout to avoid trenching on 
ground already covered by them, and have rather 
concentrated attention upon less familiar points. 
