See [page 42]
A GROVE OF BEECHES
See [page 44]
THE CHESTNUT
Leaves are the lungs of plants. In the growing season respiration goes on at a vigorous rate. The leaves also throw off in insensible vapor a vast quantity of water. This is called transpiration in plants; in animals the term used is perspiration. They are one and the same process. An average white oak tree throws off 150 gallons of water in a single summer day. With the cutting off of the water supply at the roots in late fall, transpiration is also cut off.
The skin is the efficient "third lung" of animals. The closing of its pores causes immediate suffocation. The bark of trees carries on the work of respiration in the absence of the leaves. Bark is porous, even where it is thickest.