THE FALLING LEAVES 



ward, thus giving the tree a kind of double 

 circulation. 



A tree may be no more beautiful and wonderful 

 when we have come to a knowledge of all its hidden 

 processes, but it certainly is no less so. We do 

 not think of the function of the leaves, nor of the 

 bark, nor of the roots and rootlets, when we gaze 

 upon a noble oak or an elm; we admire it for its 

 form, its sturdiness, or its grace; it is akin to our- 

 selves; it is the work of a vast community of cells 

 like those that build up our own bodies; it is a 

 fountain of living matter rising up out of the earth 

 and splitting up and spreading out at its top in a 

 spray of leaves and flowers; and if we could see its 

 hidden processes we should realize how truly like a 

 fountain it is. While in full leaf a current of water 

 is constantly flowing through it, and flowing upward 

 against gravity. This stream of water is truly its 

 life current; it enters at the rootlets under the 

 ground and escapes at the top through the leaves 

 by a process called transpiration. All the mineral 

 salts with which the tree builds up its woody tissues, 

 — its osseous system, so to speak, — the instruments 

 with which it imprisons and consolidates the carbon 

 which it obtains from the air, are borne in solution 

 in this stream of water. Its function is analogous to 

 that of the rivers which bring the produce and other 

 material to the great cities situated upon their 

 banks. A cloud of invisible vapor rises from the 



7 



