24 



THE AMERICAN BOTANIST 



equal tO' two good human lives — and yet the oak is but at the 

 point at which a man attains his majority. The oak is built up 

 after a process by which man attains his full stature. It is a 

 process of multiplication of weak, minute cells which become 

 specialized for distinct offices in the economy of the vegetable 

 community which we call a tree. Some go to renew and 

 enlarge the roots, others to perfecting that system of vessels 

 through which the crude fluid from the roots is carried up to 

 the topmost leaf, whence after undergoing chemical trans- 

 formation in the leaf laboratory, it is circulated to all parts of 

 the organism to make possible the production of more cells. 

 Each of these has a special task and it becomes invested with 

 cork or wood to enable it to become part of the bark or the 

 timber or it remains soft and develops the green coloring- 

 matter which enables it, when exposed to sunlight, to manu- 

 facture starch from carbon and water. 



The tree, as we have indicated, gets its food from the air and 

 the soil. The rootlets have the power to dissolve the mineral 

 salts from the soil in which they ramify, some authorities 

 believing that they are materially helped in this respect, so far 

 as organic matter is concerned, by a fungus that invests them 

 with a mantle of delicate threads. However that may be, the 

 fluid that is taken up is not merely water, but water plus dis- 

 solved mineral matter and nitrogen. 



At the same time that the roots are absorbing liquid nutri- 

 ment the leaves, pierced with the thousands of little stomata or 

 mouths, take in atmospheric air which is compounded chiefly of 

 the gases nitrogen, oxygen and carbon dioxide. The leaf cells 

 containing the green coloring matter, chlorophyll, seize hold of 

 the carbon and release the oxygen. The carbon is then com- 

 bined with the fluid from the roots by the vital chemistr}- of 

 the leaves and is circulated all over the system for the suste- 

 nance of all the organs and tissues. — From an article by JV. B. 

 Beach in Tree Talk. 



