24 PROPAGATION. 



I. CUTTINGS. 



When a ligature is bound closely round a branch, the ob- 

 struction which it imposes to the descending juices causes an 

 enlargement or swollen ring above the ligature, as in Fig. 19. 

 The same result is produced if a small ring of bark is cut out, 

 as in Fig. 20. If a shoot is taken from the tree before the 

 leaves expand, and plunged into moist earth till it commences 

 growth, the elaborated materials build up at the lower ex- 

 tremity a callus or ring, as in Fig. 2 1 ; and under favorable cir- 

 cumstances, roots will form above or near this callus (Fig. 22), 

 and thus a new plant is formed. 



Every leaf-bud on a fruit-tree may be regarded as an em~ 

 bryo branch, and capable of forming a tree when supplied 

 with separate roots. But single buds do not contain within 

 themselves sufficient nutriment to sustain vegetation till roots 

 are formed, without a considerable portion of the sap-wood and 

 cambium layer attached; hence the superior 

 advantage of taking an entire shoot or cutting. 



Propagation by cuttings is the simplest mode 

 of multiplying a variety. It consists in the in- 

 sertion of a shoot of one year's growth into the 

 soil ; the moisture of the soil renews the sup- 

 ply of sap, the buds swell, the leaves expand, 

 and the descending juices extend themselves 

 in the production of new roots, which shoot 

 downward into the soil, Fig. 23. 



Under ordinary circumstances, or in open 

 ground, this mode is only applicable to such 

 species as readily throw out roots, as the cur- 

 rant, gooseberry, quince, and grape. Cuttings 

 of the apple and pear can only be made to 

 strike root in the Northern and Middle States 

 by confining the moisture under glass, while 

 artificial heat is applied. 



It may be stated, in general, that cuttings made of the rip- 

 ened wood of such trees as have a large pith succeed best 

 when taken off with a portion of the preceding year's wood, 



