352 THE ROLL OF THE SEASONS 



many others is a pillar of fire, while its neighbours 

 are unflecked. Here, side by side with oaks that are 

 withering in their dour fashion, is one dressed in the 

 tender red-green of spring. The birches on the top 

 of the gravel-bank have lost their plumes, while those 

 only twenty yards below are covered with parti- 

 coloured leaves. The outer part of each has been 

 abandoned, while the base is full of the green army 

 retiring towards the twig. 



The chlorophyl grains swim in the protoplasm of 

 the cell, as the red corpuscles in the haemoglobin of 

 our blood. When the light is weak they muster 

 clamorously at the surface, for then each must work 

 its hardest to get the utmost chemical advantage of a 

 short supply. But when the sun shines strongly, the 

 leaf grows less green. A few chemists can do all the 

 work, or the flat granules only need turn an edge in- 

 stead of a broadside to the sun. The pupil of each 

 cell contracts as does the eye of the cat under similar 

 circumstances. The brightest greens are those found 

 in deep, rocky pockets, where hartstongues and liver- 

 worts eke out a laboured existence, or in darker places 

 still, where the Luminous Moss earns its name, merely 

 by the activity of its chlorophyl particles. There is 

 much to be learnt about these tiny green bodies, but 

 we do know that some salt of iron seems essential to 

 their formation. Give a plant soil that has no iron in 

 it, and it produces white leaves, which are not of the 

 least service for prolonging life. Feed it now with an 

 iron salt, and the leaves become green and serviceable. 

 Surely, then, the secret is out, and we know why the 

 leaves turn brown. Added to all that wonderful list 

 of benefits that Ruskin reminded the people of Tun- 



