1839] 



FARMERS' REGISTER. 



467 



done, the expense incurred wonltl he far more than 

 repaid him, by the additional durability of the 

 timber. 



Chapter XX. 



ClIAKGES IIV VLAKTS, PUODUCED CY PUKC- 

 TUUE OF IKSECTS, CHARGES IK CLIMATE 

 AND SOIL, GUAFTING, BUDDING AND PUT- 

 NING, CROSS FECUNDATION, BLANCHING, 

 AND PROPAGATION FROM SELECT SEED. 



When we look at culiivateil vegetables as they 

 are now presented to the eye, we seldom think of 

 the unpromising sources i'rom which most ol'them 

 have sprung ; or of the great changes which it 

 was necessary they should undergo, belbrc becom- 

 ing fit to minister to the necessities or pleasures of 

 man so largely as they now do ; or oi' the diiler- 

 ent and distant regions which have been laid un- 

 der contribution to lurnish that variety of vegeta- 

 bles possessed by the dill'erent civilised nations of 

 the earth. "The ausieie crab-apple ofour woods, 

 is the original stock from which all our apples have 

 sprung ; and the numerous varieties of plum, 

 can boast ofno other parent than our native sloe.'' 

 The fig came orisiinaliy from Syria, the orange 

 from Media, the peach from Persia, the apricot 

 I'rom Epirus, the pomegranate (i'om Africa, the 

 cherry from Armenia, wheat, probably from the 

 East Indies, maize and the potato, li-om Mexico. 

 "Wherever man has penetrated, in that spirit of 

 change and aciiviiy which acconipanies civiliza- 

 tion, he has assisted the dissemination of vegeta- 

 ble productions, much more surely and raf)idly 

 than birds, or ocean currents, or winds, or indeed 

 all natural agents put together.'" From a consi- 

 deration of such liicts as these, we mav learn to 

 how great an extent the agriculiural riches of any 

 country, whether we have regard to the excel- 

 lence of its products or to their variety, are depen- 

 dent upon man. There are but lew, if any plants, 

 which in the wild condition, are well adapted to 

 use, and there are none which may not be im- 

 proved by a judicious system of cultivation ; and 

 there is no country which can furnish any great 

 variety of useful vegetables, without levying con- 

 tributions upon other and often distant lands. 

 From all this it is evident, that although tlie <ren- 

 eral laws which frovern vegetables "are fixed, 

 yet vegetables themselves may undergo many 

 changes, both by accidents and from the arts of 

 man. A consideration of some of these changes, 

 and the means by which they are produced, will 

 be the subject ol' the present chapter. 



Among the most important ol' those causes by 

 which changes are produced in plants are, the 

 puncture of insects, change in climaie and soil, 

 grafting and budding, cross lecundation, blancl;- 

 ing, and propagating lioin selected seed. 'I'o each 

 of these subjects we will attend, in the order in 

 which it has been mentioned. 



\st. The puncture nf insects. — There are many 

 insects, whose instincts teach them to puncture 

 the bark of veirelables in order to deposiie their 

 eggs. Whereever this is affected, a diseased con- 

 dition immediately ensues in the part punctured, al- 

 ways resulting in the developement of a tumor of 

 greater or less size. This is generally accounted fi)r 

 by saying that the insect, at the satnc time at which 



it deposites its p,^(r., deposites along with it some 

 matter which is poisonous to the plant. The 

 fbrmaiion of the tumor is generally accompanied 

 with the elaboration of some particular vegetable 

 substances which would otherwise, either not 

 have been formed at nil, or else would have been 

 formed in very small (|uantities ; and in conse- 

 quence of their containing this particular substance, 

 whatever it may be, these tumors are collected 

 and used in the arts. A good instance of this is 

 afforded in the production of the nut-gall. Whilst 

 the bud of the species ol'oak on which these galls 

 are formed, is yet young, a species ol cynipg drives 

 its piercer into the very pith, and depositing its egir, 

 injects at tliesame time a small drop of a corroding 

 liquor contained in its bag. The bud being thus 

 wounded, and the juices corrupted by the injected 

 poison, a (ermentation is induced, which results in a 

 partial disorganization of all the contiguous parts. 

 The extravasated juice flows round the eg\i, and is 

 there accumulated, and converted into a sort of 

 spongy liuiip, which vegetates and augments till 

 it Ibrms the gall. The gall thus formed, furnishes 

 both shelter and nourishment to the young insect 

 so long as it remains in its larva state, but so soon 

 as it lias completed its metamorphoses, it eais its 

 way out and escapes. During the (brmation of 

 the gall, a large quantity of gallic acid is elabora- 

 ted by the diseased parts, and this it is which fits 

 the gall for its use in the arts. 



Perhaps the most curious instance of the effect 

 produced by the puncture of an insect, is that af- 

 ibrded by the 'fig. "The fig (jkus carica) has no 

 visible flower ; for the fruit arises immediately 

 from the jointsof the tree, in the form of little buds, 

 with a perforation at the end, but not opening, or 

 showing anj^-thing like petals, or the ordinary 

 parts of fructification. As the fig enlarges, the 

 flower comes to maturit}' in its concealment ; and 

 in eastern countries the fruit is improved by a sin- 

 ffularoperaiion known by the nameofcaprification. 

 This is performed by suspending, above the culti- 

 vated figs, branches of the wild fig, which are full 

 of a species of cynips. When the insect has be- 

 come winged, it quits the wild (ig, and pierces the 

 cultivated ones lur the purpose ol laying its eggs ; 

 and thus it appears both to insure theliuctification 

 by dispersing the pollen, and afterwards to hasten 

 the ripening of the fruit, by puncturing the pulp, 

 and inducing a morbid action of its tissues. In 

 France this operation is imitated by inserting 

 straws dipped in olive-oil. Respecting the punc- 

 turing of insects, it is perhaps worthy of remark, 

 that each particular species of insect appears, as a 

 general thing, to be confined to ?ome particular 

 kind of plant, and that the effect produced by each 

 kind of insect is uniform. In form, these tumors 

 dilfcr much from each other ; the nut-gall is an 

 irrirgular ball, the tumor produced upon the leaf of 

 the hickory by the puncture of the gnat, has no 

 regular shape whatever, whilst that produced by a 

 similar insect upoti the Itjaf of the grape-vine, al- 

 ways present the form of a horn and is of a beau- 

 tiful purple color. The time which elapses be- 

 tween the deposition of the egg, and the appear- 

 ance of the insect, varies much in the case of' di!'- 

 lerent species. The egg which is dijposited in the 

 pea whilst yet green, is seldom hatched out until 

 the succeeding summer ; whilst other species ap- 

 pear in the coarse of a very few days. 

 2/irL Changes in clhnalc. — Thuugii j^laiits in 



