CHAPTER V 



CHLOROPHYLL 



CHLOROPHYLL— THE OXYGEN AND CARBON DIOXIDE 

 CYCLE— MINERAL OIL AND NATURAL GAS- 

 HAEMOGLOBIN 



La matiere verte des vegetaux..,.Nous proposons de lui donner 

 le nom de chlorophyle. Pelletiee et Caventou (1828). 



When I want to know why a leaf is green, they tell me it is 

 coloured by "chlorophyll," which at first sounds very in- 

 structive; but if they would only say plainly that a leaf is 

 coloured green by a thing which is called " green leaf," we should 

 see more precisely how far we had got. 



RusKiN, Queen of the Air (1869). 



Chlorophyll 



A GREAT annual miracle occurs each spring-time in the 



temperate regions of our world. The "boyhood of the year" 



grows up. Amongst flowering plants, the snowdrops and 



crocuses, the anemones and daffodils take the lead; amongst 



the trees the elder and the horse-chestnut usually begin it. 



Tennyson tells us — ■ 



The tender Ash 

 Delays to clothe herself when all the woods are green, 



In the autumn she is loath to lose her leaves, and they lin- 

 ger on when other trees are stripped of their green mantle, 

 though the leaves rarely hang long enough to turn yellow. 

 In the course of a few weeks most of our trees and shrubs and 

 plants have clothed, as it were, the earth A\dth a green carpet ; 

 green, the colour of hope. 



What is it that causes this wonderful verdure? It is a 

 substance called Chlorophyll, the most wonderful substance 

 in our world. A world without chlorophyll would be a world 

 without the higher forms of life, and in such a world no life, 

 save perhaps that of the lowest bacteria, could possibly endure. 

 In fact, without this remarkable pigment the living world as 

 at present constituted could not exist. 



