186 AUTUMNAL LEAVES. 



occasions the almost endless shades of other 

 colours. 



In relation to this subject of the colouring pig- 

 ments of plants a subject which is one of great 

 interest the accomplished naturalist and writer 

 whose name has just been mentioned has an able 

 chapter on ' the colours of plants and the origin of 

 the colour-sense ' * in his work c Tropical Nature ;' 

 and as he there epitomizes so much on the ques- 

 tion as recent science has discovered, it will be well 

 to make a short extract from the chapter in ques- 

 tion. Mr. "Wallace says : e The recent investiga- 

 tions of Mr. Sorby and others have shown that 

 chlorophyll is not a simple green pigment, but 

 that it really consists of at least seven distinct 

 substances, varying in colour from blue to yellow 

 and orange. These differ in their proportions in the 

 chlorophyll of different plants ; they have different 



* The origin and development of the colour-sense is a subject 

 of considerable interest and importance. It is, however, too 

 extensive to be pursued in these pages, and is, moreover, out- 

 side the purpose and object of this volume. But the reader 

 who desires to study it is referred to the writings of Mr. Alfred 

 Russell Wallace and to the able and interesting volume on * The 

 Colour-sense ' by Mr. Grant Allen. 



