THE AMERICAN BOTANIST. 
9 
poses much less surface, but why should it be necessary to 
so quickly pull in sail ? Contrast the open and closed leaves 
and note how changed is the aspect of the plant! 
Movement of leaves reaches its acme in that vegetable 
wonder — the Venus' Fly-trap, Dionaea muscipula — a plant 
nearly related to our familiar sun-dew, but confined to a 
restricted region about Wilmington, N. C. In this, the 
blade as it may be called for convenience, consists of two 
lobes, each cut into sharp teeth on the margin and having 
the teeth of one side interlocking with these of the opposite. 
Indeed, the whole contrivance looks like and acts as a trap. 
The opposed lobes each have on their inner face three sensi- 
tive hairs. When these are touched, as by a fly or ant, the 
trap at once closes, and the more the creature struggles, 
the more closely he is held. Then, finally he is digested. 
The kindred sundew, also a gay trap, shows movement only 
in the disk-crowned, sticky hairs, which clothe it. This 
plant, too, is insectivorous. 
Other movements in leaves might be cited, but already 
I exceed my space. In closing, let me add that the final 
movement, ''the fall of the leaf" is only so far inherent, 
that it is provided for early in the season by the "absciss 
layer", a depression or line of separation that deepens as the 
season advances. Finally gravity alone, or freezing of 
moisture in this layer is enough to cast off the leaf. Some- 
times, as with horse-chesnut, where yesterday stood a tree 
still fully clothed, there is today merely the undraped body — 
the skeleton even of the tree. 
Brozvn Univ., Providence, R. 1. 
A WORD CONCERNING TREES. 
BY FRANK DOBBIN. 
IT was Oliver Wendell Holmes who said that: "the elm 
came nearer having a soul than any other American 
tree." It is indeed one of the most stately and graceful of 
