34 



HISTORY OF THK VEGETABLE KINGDOM. 



liber of the graft should correspond in the greater 

 part of its extent with that of the stock on 

 which it is inserted. 



Grafting hy scions is managed in several ways. 

 Sometimes the head of the stock is split into 

 two, and the twig to be grafted is inserted in the 

 slit. This operation is known by the name of 

 deft-grafting. Sometimes the bark is separated 

 from the subjacent woody layers, and several 

 small twigs disposed in a circular manner be- 

 tween tliem. This method is named crown- 

 grafting. At other times the trunk of the tree 

 is perforated, and a young branch fitted and 

 permanently fixed to it. This method, which 

 is now little employed, bears the name of wimble- 

 grafting or peg-grafting. Occasionally grafting 

 by scions is practised upon young twigs covered 

 with leaves, flowers, and even young fruits. In 

 this case, it is effected during the full flow of 

 the first sap. By this process, it is not uncom- 

 mon to obtain fruit from a tree fifteen or twenty 

 years sooner than it would otherwise have pro- 

 duced it. It has even happened, that, in sowing 

 a seed at a particular period, ripe fruit has been 

 obtained fi-om it before the end of the year. 



Grafting by scions is also practised without 

 cutting off the head of the stock, a notch being 

 made on one of its sides, to which the graft is 

 applied. This is named side-grafting, and is 

 principally used for the purpose of repairing 

 the head of a tree which has lost some of its 

 branches. 



Lastly, to this section may be referred the 

 grafting which is performed with a scion upon 

 a root left in its place, or with a root upon the 

 root of another stock. 



3. Grafting hy huds. This consists in trans- 

 ferring to another individual a plate of bark to 

 which one or more buds adhere. Of this kind 

 also is scutcheon-grafting, flute-grafting, and 

 other varieties. Bud-grafting is the most gen- 

 erally practised, especially for multiplying fruit- 

 trees, it being more easily and expeditiously per- 

 formed than any other operation of this nature. 

 It is performed in spring, at the time when the 

 sap ascends, or in August. The form to be given 

 to the graft, and that of the incision, vary greatly 

 according to the peculiar mode employed. 



4. Grafting of herbaceous parts of vegetables. 

 The discovery of this kind of grafting dates 

 from a recent period, a few yeai-s only having 

 elapsed since it was for the firat time practised. 

 It may be performed with the young herbaceous 

 shoots of trees, during the full flow of the sap, 

 or with annual plants. In order that this graft 

 may succeed, it must be inserted into the axilla, 

 or into the vicinity of a living leaf of the stock. 

 This leaf serves to draw the sap into the graft, 

 and to facilitate its union and development. The 

 methods employed are much the same as for the 

 other kinds of gi-afting. 



Size of trees. Trees are, in general, larger 

 and taller, in proportion as the climate and the 

 situation in which they gi'ow are adapted to 

 their nature, and prove favourable to their de- 

 velopment. A certain degree of humidity, 

 joined to a pretty high temperature, appears to 

 be the circumstance most favourable to the 

 growth of trees ; and in regions possessing these 

 conditions of the atmosphere, they attain the 

 greatest height. The forests of South Americji 

 are, in general, composed of trees gi-eatly ex- 

 ceeding ours in their bi-eadth and height, and the 

 beauty of their foliage and flowers. 



Certain trees take a long series of years in ac- 

 quiring any considerable height or diameter ; 

 as the oak, the elm, and the cedar. Others, on 

 the contrary, gi'ow much more rapidly. They 

 are chiefly trees which have light and softwood, 

 as poplars, pines, Acacias, &c. Lastly, there 

 are plants which grow with such rapidity, that 

 the eye can, in a manner, follow the progress of 

 their development. Of this kind is the agave 

 A mericana, or American aloe. This plant, which 

 covers the rocks along the shores of the Medi- 

 teiTanean, in the gulf of Genoa, when it flowers, 

 shoots out a stalk which sometimes acquires a 

 height of thirty feet, in the space of thirty or 

 forty days, or even less. As it gi-ows about a foot 

 in a day, its successive development should be 

 perceptible to the observer. 



In general, the greatest height which the trees 

 of our forests attain is from 120 to 130 feet. 

 In America, palms and many other trees often 

 exceed 150 feet. Trees vary as to their diameter, 

 not less than in height. Some of them occa- 

 sionally acquire monstrous dimensions. 



In Britain, oaks of a great age have been known 

 to measure upwards of forty feet in circumfer- 

 ence at the base of the trunk, with an elevation 

 of ten or twelve feet without any division. At 

 Colthorpe, near Wetherby in Yorkshire, there 

 is now growing an oak that measures seventy- 

 eight feet in circumference close to the ground, 

 and forty-eight feet at the height of a yard. 

 It is said to have begun to decline in the reign 

 of Queen Elizabeth, and though now much in 

 decay, is still likely to stand for many years. 



The araticaria, a pine of Norfolk Island, is 

 found of the extraordinary height of 267 feet, 

 the width at the base being twelve feet, while at 

 the height of eighty feet it continues of the same 

 diameter. Breton * describes another tree in New 

 South Wales, having a triangular trunk, one 

 side of which was eighteen feet in width ; 

 another nineteen feet, the third twenty-two" feet; 

 making a total width of fifty-nine feet. 



" I measured," says Mr Darwin, "one of those 

 noble trees called the Kauri Pines, in a part 

 which was not enlarged near the roots, and found 



* Sketches of New South Wales. 



