COLOUR. Ill 



ether; in a solution of carbonate of soda it becomes 

 of a yellow colour, whilst concentrated sulphuric acid 

 changes it to an intense blue. 



146. According to Macquart, Chlorophyll furnishes 

 a blue colouring matter by the addition of water, 

 and a yellow on the subtraction of water. The 

 blue colour, or anthokyan, is the primitive one in all 

 blue, violet, red, brown, and orange colours seen in 

 plants ; it loses its colour by much exposure to the light, 

 is turned green by alkalies, and red by acids, carbonic 

 acid being sufficient for this purpose. The yellow co- 

 lour, or anthoxanthin, is the base of all yellow colours, 

 and is rendered blue by the action of sulphuric acid. 



147. These two primitive colours in various states of 

 power can exist in the same petal, though contained in 

 different layers of cellules ; the anthokyan being in 

 the uppermost range, and the anthoxanthin in the 

 lowermost cells ; "by which means," says Macquart, 

 " great variety is produced in some plants having coloured 

 flowers." 



148. Besides anthokyan and anthoxanthin it was 

 found that in all white flowers there exists a yellowish 

 white, or pure white substance, called by Macquart 

 flower resin, and which he looks upon as a transitional 

 state between chlorophyll and anthokyan, and con- 

 siders that the white colour of plants must be regarded as 

 a transitional state of green towards blue. 



149. Various as are the differences between the 

 colours of plants and their separate portions, they may 

 be all more or less reduced to two separate series, at the 

 head of which green is to be placed. The green either 

 changes into yellow, this yellow into orange, and the 

 orange into orange-red ; or into blue, and this blue into 

 violet, and the violet into violet-red. The fundamental 

 tone in the one series being blue, and in the other yel- 

 low, and these two colours in the vegetable spectrum 

 generating green. 



