SECRETARY'S REPORT. 149 



sluggish. Leaf-buds sometimes remain dormant for years ; they 

 may even be covered up by succeeding growths of wood, and yet 

 b}' severe pruning may be forced into growth and develope into 

 branches. > 



The leaves constitute the foliage of the tree. A leaf is an ap- 

 pendage to the stem, and has a leaf-bud in its axil. It consists of 

 an expansion of the cellular rind of the bark, through which are 

 distributed veins, or tough woody fibres, like ribs, and over all is 

 an epidermis or skin. Through this skin respiration, perspiration 

 and absorption take place. The office of the leaf is analogous to 

 that of the stomach and lungs in animal life. The tree does not 

 got its food wholly from the root. A portion of it is obtained by 

 the leaves from the air. Tin's, with what comes from the root, 

 through the stem, dissolved in sap, is here exposed over a large 

 surface to the action of sunlight, air and other external agencies, 

 by which, in connection with vital action, the crude materials are 

 elaborated and digested, and returned to the general circulation to 

 be assimilated, and go to form root, wood, leaf, seed and fruit. 



If it were proper to say that one organ is more necessary than 

 another, when all are indispensable, we might give this distinction 

 to the leaf, but this, we may certainly affirm, that the functions of 

 the leaf are essential to the healthy existence of the plant, and that 

 whatever disturbs their free and normal action diminishes its health. 

 Some persons, ignorant of this, have been so foolish as to .strip a 

 grape vine of its leaves, with an expectation of hastening the ma- 

 turity of the fruit by the admission of inore light and air. The 

 fact is, that sunlight and air influence the ripening of the fruit indi- 

 rectly, and by their action upon the plant through its leaves. By 

 ill management the leaves on a vine may and often do become so 

 numerous and crowded as to prevent a proper discharge of their 

 functions. In such case the early removal of a part, by allowing 

 the more perfect development of a suitable amount of foliage, will 

 be found beneficial. 



In spring the opening of the leaf-buds is accompanied by the 

 extension and increased action of the spongioles of the root, and 

 the action of the leaves upon the roots and of the roots upon the 

 leaves, throughout the whole season, is constant and mutual. Cut 

 off all the spongioles from a tree in full growth, and the foliage at 

 once withers and dies. Let the leaves be destroyed by a blight or 

 removed by design, and growth is at once suspended, the action of 



