74 LIFE OF A TREE. 
from the over-powering glare; and this took place 
in every experiment conducted on the subject, 
—thus evidently shewing that the red light con- 
tained some principle, to the presence of which 
vegetation shews the greatest aversion. 
These considerations lead us to another and 
more remarkable feature of the vegetable life. 
We have said above, that when a plant first 
pierces the soil, and clambering through the yield- 
ing particles. of brown earth lifts up its tender 
stem to the gaze of day, it consists almost ex- 
clusively of cellular tissue, and is therefore as 
fragile as possible. To become useful in the world 
of Nature, and for the purposes of man, it must 
undergo an important change of nature ; in other 
words, it must become wood. 
Now it is a beautiful truth, that no sooner 
does the plant see the light than this indurating 
or hardening process actually commences; shew- 
ing us that all things have been so harmoniously 
ordered, that no sooner do circumstances call for 
an alteration in the constitution of the plant, 
than a fresh chain of events is set in motion to 
effect this very end. Down below the earth the 
firm woody tissue was unnecessary ; for there no 
