168 PLANT LIFE 
breaking up of the complex substances 
constituting the dead bodies of other organ- 
isms into simpler chemical compounds, and 
sometimes even into their elements. They 
utilise a certain amount of the energy thus 
finally set free in building up the materials 
of which their own bodies are constructed, 
but the proportion of matter (and of energy 
too) thus locked up again is extremely small 
when compared with that which has been 
liberated in the process. 
Regarded from this standpoint the sun is 
seen to be the very fountain of life and power. 
The complex materials which jostle each other 
as they are borne down the stream of life 
break down here, provide the power for 
synthesis there, but on the whole are ever 
losing more of their energy, for some is 
continually dissipated as heat. Many of the 
useless molecular fragments which drift out 
of the stream of life are presently caught up 
again at the fountain-head, the chlorophyll 
machinery driven by the solar energy once 
more draws them into the mill, there they 
are broken up, are compounded with other 
ingredients, and the whole turned out once 
more as_ energy-containing carbohydrate. 
Again the compounded matter re-enters the 
stream of life, to part, little by little, with 
the energy it contains. Some is destined to 
reappear in vital units of almost infinite 
complexity, the rest is utilised or lost in 
various ways, and the broken and buffeted 
