CHAPTER II 
SEAWEEDS AND LEAF-GREEN 
THE major planet Earth probably differs from all its 
companions in space in one special respect. 
It is a “green” world, and this colour is no acci- 
dental ornament, but is the real fountain and origin of 
all the life that swarms upon its surface. 
Not only the growth of plants, but all animal and 
human activities—the soaring of a hawk, logical 
reasoning, or any kind of mental or emotional strain 
—depend upon this peculiar green substance “ chloro- 
phyll.” 
One cannot exactly say that the world depends upon 
chlorophyll in the way that a motor is “run” by petrol, 
for this chlorophyll may not be used up in the process. 
It is a sort of chemical sensitiser which absorbs certain 
kinds of sunlight. That is, the energy of their vibra- 
tions is intercepted and turned to another form of 
work, 
Our food, which is necessary for every strain of nerve 
or muscle, consists of animal and vegetable matter, 
and this last represents the life-work of chlorophyll or 
“leaf green.” 
We cannot give more than a very general idea of the 
way in which the chlorophyll works. The coolness and 
shade under a beech tree even in very hot weather is 
enough to show that the leaves have somehow inter- 
cepted most of the sunlight. To follow the process a 
little more cldsely, one must imagine a leaf with the 
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