Page:Cyclopaedia, Chambers - Supplement, Volume 1.djvu/820

 G R A

G R A

of the writers in agriculture pretend. This author obfervcs, however, that this anatomical obfervation alone would not have convinced him of the falfity of too many of thefe re- lations, had not experiment joined to confirm it ; he tried many grafts on different trees, and, for fear of error, re- peated every experiment of confequence feveral times, but all ferved only to convince him of the truth of what he at lirft fufpected. He grafted in the common way the peach upon the almond, the plum upon the apricot, the pear upon the apple, the quince, and the white thorn, one fpecies of plum on other vefy different fpecies, and upon the peach the apricot and the almond ; all thefe fuccceded alike, the fpecies of the fruit was never altered, and in thofe which would not come to fruit, the leaves, the wood, and the Mowers, all were the fame with thofe of the tree from which the graft was taken.

■Authors in agriculture have mentioned alfo a very different fort of grafting, that is the letting grafts of one tree on ftoclcs of a different genus of trees ; fuch as the grafting the pear upon the oak, the elm, the maple, or the plum ; the mulberry upon the elm, the quince, and the fig ; the cherry upon the laurel ; the peach upon the hazel ; the vine up- on the cherry tree, and upon the hazel ; and the like un- natural conjunctions. Mr. Du Hamel tried all thefe fcparate- ly, and carefully, and the event proved very plainly, that tlrofe who had mentioned them had never tried them ; and a natural conclufion from this was, that there muff be a natu- ral alliance between the graft and the flock which receives it, otherwife it will either never grow at ail, or elfe very foon perifh. Memoirs Acad. Par. 1727.

The facility with which grafts take place, and grow on pro- per nibjects, is well known ; there are, however, many acci- dents and uncertainties attending them in their different pe- riods. Some perifh immediately, fome after appearing healthy for many months, fome even after years of health. Of thefe laft fome die without the Mocks fuffering any thing; others perifh together with it. It is very certain, that the greater part of grafted trees do not live fo long as they would have done in their natural Mate, yet this is no unexceptionable rule, for there are fome which evidently live the longer for this pradtice ; nay there are inftances of grafts, which being placed on frocks naturally of fhort duration, live longer than when placed on thofe which are more robuft and lafting. Thefe are irregularities which have been little confidered hitherto, though they happen in a practice, the advantages of which are very great. One great requifite for the fuc- ceeding of any graft is, that it be in its own nature capable of fo clofe and intimate an union with the fubftance of the ilock, that it becomes as it were a natural branch of it,, i If all trees refembled one another in their ftruclure and juices, if their folid parts were all of the fame figure, and their fap all of the fame nature and confiftence, their veffels all of the fame diameters, and their elafticity, and the number of the trachere equal in all, and in all filled with the fame quanti- ties of air ; if trees were alike in thefe particulars, probably grafts of all trees would fucceed upon one another, but this is by no means the cafe.

Trees are well known to be compofed of numerous ar- rangements of hollow fibres, and thefe are different and un- equal in every fpecies of tree. In order to the fucceeding of a graft, it is evident that there muft be a mutual confor- mity in its velTels and juices with thofe of the flock, and the more nearly they agree in this, probably the better they fucceed ; and the farther they differ, the worfe. If there be, however, fome difference in the folid parts of trees, there arc evidently many more in their juices. The fap in fome trees is white as milk, in others it is reddifh, and in others clear and limpid as water ; in fome it is thin and very fluid, in others thick and vifcous. In the tafte and fmell of thefe juices there are alfo not lefs differences ; fome are fweet, fome bitter, fome infipid, fome acrid, and fome foetid ; the differences in one or other clafs are varied al- mofl to infinity, and the fuccefs of grafts may very ratio- nally be fuppofed owing to the agreement between the juices as well as ftruaure of the graft and of the flock. The quality of the ftp thus makes a very great difference in the nature of trees, but its quantity, and readinefs of derivation to the parts, is fcarce lefs obfervable. In this we have fa- miliar inftances in the willow and the box, one of which will pufh out longer ihoots in a year than the other in twenty.

Another difference yet more linking, and indeed more ef- fential in regard to the growth of grafts than all thefe, is the different feafon of the year at which different trees fhoot out ■their leaves, or ripen their flowers. The almond tree is in flower before other trees in general have opened their ear- lier! buds, and when other trees are in flower, this is full of leaves, and has its fruit fet before the mulberry begins to pufh out its buttons. When we confider all thefe differences in trees, we cannot but wonder how it is poffible for a branch of one to live upon another; and it becomes a much more perplexing qucilion, how any graft can fucceed, than how fuch numbers come to mifcarry. A graft of one pear upon the flock of another of a different kind, fhall be feen to grow rmmediatcly, as if upon its own tree, and in a fort-

night to gain fix inches in length, and fo of fome others. This mull be owing to the great fimilarity between the flock and the graft in all refpects ; and a great contrariety, or dif- ference in the ftrufiure of parts, will make as remarkable a want of joining on the other hand. An inflance of this may be had in the plum and the elm, which no art can ever make to fucceed with one another, whether the plum be grafted on the elm, or the elm on the plum flock. Thefe are examples of the extremes of eafy growth, and of abfo- lute decay ; but there are many conjunctions of trees which feem of a middle nature between the two, and neither im- mediately perifh, nor totally fucceed. Of thtfe, fuch as were grafted in autumn ufually remain green the whole winter without pufhing, and thofe which are grafted in fpring re- main greeit a month, or longer, but ftill without mooting. Some particular ones have been alfo known to make fome fhoots the firfl, or even the fecond fap feafon after the ope- ration, but all periffi at the end of thefe times. Of this kind are the grafts of the pear tree upon the elm, the maple and the hornbeam, and the mulberry upon the elm, and upon the fig, with many others.

When we come to enquire into the caufe of this, we find that thefe grafts, though unnatural, have yet had a commu- nication with the flock by means of a few fmall veffels, which has been fufiicient to keep them green, or even to make them fhoot a little during the great afcent of the fap : But the far greater number of the fibres have had all the while no communication, and are found putrified, dried up, or covered with a putrid juice. This has evidently happened' by means of the difproportion in fize between the veffels of the flock and of the graft, and the great difference between their natural juices, which are obflacles abundantly fuffici- ent to prevent either an union of the fibres, or the intro- duction of new lap.

The grafts of the almond on the plum, and of the plum on the almond, always grow very vigoroufly for the firfl year, and give all the appearance imaginable of fucceeding en- tirely, yet they always perifh in "the fecond, or elfe fn the third year. The almond graft upon the plum flock, always pufhes out very vigoroufly at firfl, but the part of the flock immediately under the graft grows fmallcr, and perifhes ; the graft abforbing too much of its juices, and the graft ne- ceffarily perifhes with it. The decay of the whole o-cnerally happens early in the fpring, and that plainly from the diffe- rent feafon of the natural mooting of the two trees, the al- mond pufhing very vigoroufly, and confequcntly draining the flock of its juices, at a time when, according to its na- ture, the juices ate but in fmall quantity in it, and the fap does not begin to afcend. The grafts of the plum on the almond are, from the fame caufe, furnifhed with an abun- dance of fap, which they have at that time no occafion for, and confequently they as certainly perifh of repletion, as the other of inanition. Mem. Acad. Par. 1730. The peach grafted on the plum fucceeds excellently, and lives longer than it would have done in its natural flate. The reafon of which is this : the peach is a tender tree, it fhoots with great vivacity, and produces more branches than the root is able to maintain, which is the reafon why peach trees are ufually full of dead wood, and often their large branches perifh, and fometimes their whole trunk ; on this occafion, the plum being a flow fhooting tree, commu- nicates its virtue to the graft ; and the peach confequently fends out fhoots, which are more robuft, and flrong, and are no more in number than the root is able to fupply with nourifhment ; and confequently the tree is more flrong and lafting. Ibid. Tools neceffary for grafting. In order to grafting, a perfon muft be provided with the following tools. 1. A neat and fmall hand-faw to^cut off the heads of large flocks. 2. A flrong knife with a thick back, to make clefts in the flocks. 3. A fharp penknife to cut the grafts. 4. A grafting duf- fel and a fmall mallet. 5. Brafs firings, or elfe woollen yarn to fallen on the grafts with, and finally, a quantity of clay, which fhould be prepared a month before it is ufed, and kept turned and worked about every day like mortar. The beft mixture for this matter is : a quantity of flrong, fat and vifcous loam muft be got, and into this muft be well beat and mixed fome ftone-horfe dung, and fome chopp'd ftraw cut very fhort and fmall ; finally, a quantity of common fait muft be thrown in, this muft be mixed up and beat together into a parte with water, but it muft not be ex- pofed to the frofts. This is equally proper to be employed for all the different forts of grafting. Miller's Gardners DiS. Principal hinds of grafting, are, 1. Grafting m ■Cat: x\ni, called alfo {houlder-grafting, and by fome crown-grafting ; this is only fit for large trees, and the grafts in this are let in form of a circle or crown. This is mofl properly per- formed in rhe latter end of March or beginning of April. 2. Cleft -grafting, which is alfo called by fome flock and Bit-grafting. This is proper for flocks or trees of a leffer fize, and not exceeding two inches in diameter. This grafting is to be performed in the months of February and March and Ripply the failure of the efcutcheon way, which is ufually performed in June, July, and Auguft.

2 3. Whif-