PLANTS DEFEND THEMSELVES 35 
struggling against the stronger; the stronger mer- 
cilessly crushing the weaker. The contention 
among plants is bitter and frequently cruel. In 
addition, they must survive the ravaging onslaught 
of the all-destroying human kind. The extent to 
which they progress in overcoming these obstacles 
marks their success or failure in the struggle of 
life. 
The habitat of plants largely decides their type 
of difficulties and dangers. Thus the air plant is 
immune from the pests which force the desert plant 
to protect itself with daggers and prickles; aquatic 
plants rarely are troubled with creeping, wingless 
insects or burrowing grubs; arctic plants, such as 
mosses and lichens, need no defence against moths 
and tropical pests; while plants like dandelions and 
milkweeds, which send their children out into the 
world by means of airships and balloons, have no 
fear of city congestion. So all plant life, as all 
animal and human life, has been wisely created, 
protected from certain dangers by its environment, 
and provided with a means of defence against those 
other dangers to which its environment subjects it. 
For none is the burden made too heavy; for all is 
the necessity to struggle in order to grow and live. 
In the plant world as in the human world there is 
a law of compensation. 
