152 LIFE OF A TREE, 
The subject, it must be acknowledged, is one of 
great obscurity. 
Arum Maculatum. 
At the time of 
flowering in some 
trees and _ plants, 
there is a very re- 
markable evolution 
of heat, which we 
shall be better able 
to account for. It 
will surprise many 
readers to learn that, 
when some plants 
are just expanding 
their flowers, these 
beautiful organs be- 
came quite warm. 
The curious plant 
here figured, the 
Arum, presents us 
with one of the most 
marked cases in 
point. One of the 
species growing in 
the Isle of France was found, upon experiment, 
