34 THE ZOOLOGIST. 



being seriously studied. When we remember the deadly effects 

 of such " waste products " on the higher vertebrates, and that 

 the yellow pigment found in the wings of many of the Pieridse 

 are due to " modifications of the ordinary waste products of the 

 organism," we are forced with the authoress to suppose " that 

 the wings of butterflies, being relatively non-vital parts, can have 

 poisonous substances stored up in them without injury to the 

 organism, and that therefore the utilisation of waste products as 

 colouring agents can only occur in cases where the coloured 

 structures are not intimately connected with the blood system." 



The standpoint of this book is the physiological demonstra- 

 tion of animal colouration, the nature and elements of the colour 

 itself, and not its evolutionary life-purposes. This treatment is 

 neither sympathetic with, nor destructive to, the general concep- 

 tion of Protective resemblance and Mimicry. Colour alone must 

 of course fall under the domain of Physiology and Chemistry, as, 

 and in the same sense, all animal structure does, but this treat- 

 ment does not explain its development in variety and markings ; 

 it only gives us its composites, and does not demonstrate its 

 action as a force in the struggle for existence. In the last 

 chapter, which is devoted to a discussion of " The relation 

 of facts to theories," a rapid survey is given of the principal and 

 perhaps most popular lines of modern speculation, and if Miss 

 Newbigin has not come to bless, at all events most naturalists 

 will agree with her concluding sentences :".... in spite of the 

 fluency with which so many people talk of the meaning of colour 

 in organisms, the subject is as incomplete on the theoretical as 

 on the physiological side. It seems reasonable to believe that 

 the two deficiencies are related, and that a little more physiology 

 will arm the theorists with better weapons. In the meantime, 

 we cannot end a book on colour more fitly than by an appeal for 

 more facts." 



This volume contains many facts relating to animal coloura- 

 tion, and can be studied as well by a naturalist with a theory 

 as by one who possesses it not. The bibliographical references 

 at the end of the volume will assist a student of this fascinating 

 subject. 



