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. 



