remaining ; 



A 



health. As alfo how abfurd that common pra.^ice 

 is, of feeding down Wheat in the winter and Ipring 

 with fheep ; for by fo doing, the ftalks are rendered 

 very weak, and the ears are in proportion fhortcr ; 

 nor are the grains of Corn fo plump and well nou- 

 riHied, as that which is not fed down upon the fame 

 ground : this* is a fad which I can afTerr from many 

 years experience -, for when Corn or Grafs is icd 

 down clofe to the root, the fucceeding blades will 

 be much finer than if the firft Leaves had been left 



which is evident from all fhecp paftures, 

 where the Grafs is much finer and ihorterthan in 



" ' other places ; as alio upon lawns and bowling-greens, 

 where the Grafs is often mowed, the blades will be 

 rendered finer in proportion to the frequency of mow- 

 ino- it, yet thefpecies of Grafs is the fame with that 



'. on the richeft paftures ; fo that although this may be 



■ft defirable' thing for lawns, &c. in gardens, yet 



where regard is had to the produce, this fhould be 



avoided. 

 * Befides thefe, there are other ufes for which Leaves 

 ' are dcfigned, one of which is that of fhading the buds 

 for the future flioots from the fun, which would ex- 

 hale and dry up all their moifture, as alfo the (hading 

 of the young fruir, which is abfolurely necefiary du- 

 ring the time of their growth •, for I have fufpended 

 the Leaves of trees which were growing againft walls, 



■ fo as to expofe the fruit to the fun, and not taken 

 any of them off the branches, yet I have always found 



■ \thofe fruits fo expofed, have been greatly ftinted in 

 ^ their growth, and have never arrived to near the 



fize of others above and below them on the fame 

 "branches, nor were they fo well tailed, or replete 



with juice. . ^ " 



In making this experiment, I was as careful as pof- 



' fible not to reverfe the furfaces of the Leaves, having 



been thoroughly convinced, from many re 



perirnents. How prejudicial that is to all plants; but^ 



notwithftandine; this precaution, the event was as be- 



,^ fbre-mentioned. "r^r^-. . .:-;^d^ ^^Bl:^/- v"^'^^^^ ' 

 V,*-^notfe principal ufe of the Leavesls to throw off 

 ^**"By tfanfpiration, what is unnecefTary for the growth 

 "of the plants, anfwering to the difcharge made by 

 ^ :;. /weat in animal bodies ; and as plants receive and 

 ir' tranfpife much more, in equal time than large an i- 

 ' "v* mals, fo It appears 1i6w nefceffary the Leaves are to 

 preferve the plants in perfeft health •, for it has been 

 ' found by the mofl exad calculations, made from re- 

 peated experiments, that a plant of the Sun-flower re- 

 /. ceives and perfpires, in twenty-four hours, feventeen 

 . ' times more than a man. 



As naturalifl:s have generally afcribed a four-fold ufe 

 to Leaves, I ihall beg leave to mention them here. 



\ - 



cx- 



t 



1^ 



* / 



♦ *■ 



by die 



new 



■ 



-<- ^ 



A 



the arterial veflcls, exhaling naturally, are k^n to re- 

 turn into the trunk, 



3. That the bibulous vefiels, dried by the diurnal 

 heat, and for this reafon to be compared to veins 

 may imbibe, in the night-rime efpecially, thofc wa- 

 tery pares, wiiich, among others, lie hid in the air 

 under the form of a very tlun dew, and fo make 

 amends for the lofs made by the aiteries 

 moifture received. 



4. Laltly, the Leaf fcrves chiefly for this purpofe, 

 that it may keep and nourilli the eye, or aein, until 

 the gem, by degrees growing out to a grelcer'bulk, 

 preffes together the vefTcls of the foot-ftalk, from 

 Y/hence the humour is by Iktle and little ftoppcd in 

 the Leaf, till it cannot any more return to the foot- 

 llalk -, which, by the ceafing of the afflux and refiiix 

 of the nutritive juice, grows putrid, whence a con- 

 fumprion being caufed, the Leaf dies, and falls off 

 which is the chief caufe of the falling of the Leaves 

 in autumn. 



The Rev. Dr. Hales, in his excellent Treadfe of Ve- 

 getable Statics, fpeakin^of the perfpiration of plants, 

 gives an account of the following experiments, viz. 

 That in July or Auguft he cut off feveral branches of 

 Apple-trees, Cherry-trees, Pear-trees, and Apricot- 

 trees, two of a fort ; they were of feveral fizes, from 

 three to fixfeet long,withproportionaIlateral branches, 

 and the tranfverfe cut of the largeft part of the ftems 

 was about an inch diameter. -- ' - 



That he ftripped off the Leaves of one bough of each 

 fort, and then fet their ftems in feveral glaifes, pour- 

 ing in know^n quanrities of water. 

 The boughs with Leaves on them imbibed fome fif- 

 teen ounces, fome twenty, twenty-five, or thirty, in 

 twelve hours day, more or lefs, in proportion to the 



- quantity of Leaves they had, and when he weighed 

 . jthem at night, they were lighter than in the morning. 

 While thofe without Leaves imbibed but one ounce, 

 and were heavier in the evening than in the morning, 

 they having perfpired little. - 



V •-,/;■, 





anf tlien fhall givd an account of the moft accurate 

 'experiments which have been made to afcertain the 



'truth of their hypothefes. * ^ 



I , Chiefly, that they do in the Ipring time receive 



the crude humours into ttiemfelves, divide them very 



minutely,* and move them ftrongly in tKe utricles, and 



perhaps draw iii from the air what is neceflTary, though 



unknown to us, and carry back great plenty of elabo- 

 V :- \ rate luice to the plant. ■ " * " " ^ v:. t * *" r 

 .,r:j„,2.^ That there may be a tranipiration or what is un- 



.^4'; .rpTofit"^ble,'lhTwering to the dilcharge made by fweat ; . ^.* *u, ,vx^i.wv.u ..^.^.v^, «..^ ^...^^^ 

 -s^!^/iox^m^xSxt\^ thofe excretory vefl'els of the Leaves are j fourths of an ounce in two days. 

 ;.^Mf' fo,oyercharged by the great plenty of dift:ending hu- ' "" ' ' ' " ' ^ '* 



A:^j?mour fiuice,] that they bum in the middle, and let 

 > -'<:■: go the more lubtile parts ; nor is itlcldom, that, m a 





^ 



'The quantity imbibed by thofe with Leaves de- 

 creafed very much every day, the fa;p-vefi"els being 

 probably ftirunk at the tranfverfe cut, and too much 

 faturate with water, to let any more pafs, fo that ufu- 

 ally in four or five days the Leaves faded and wi- 

 thered much. 



He adds, that he repeated the fame experiments 

 with Elm branches. Oak, Ofier, Willow, Sallow, 

 Alpen, Currant, Goofeberry, and Filbert branches, 

 but none of thefe imbibed fo much as the' forego- 

 ing, and feveral forts of Evergreens very much lefs. 

 He adds alfo another experiment : That on the 15th 

 of Augufl:, he cut off a large Pippin with two inches 



,ftem, and its twelve adjoining Leaves: that he 

 fet the ftem in a little phial of water, which im- 

 bibed and perfpired in three days one third of an 

 ounce. ': ' • -=. . ■ >4 L::..^ 



And that at the fame time he cut off from the fame 

 tree another bearing twig of the fame length, with 

 twelve Leaves, ao Apple on it, which imbibed in 

 the fame three days near three-fourths bfarT'ounce, 

 That about the fame time, he fet in a phial of water 

 a fliort ftem of the fame tree, with two large Apples 

 on it, without leaves, and they imbibed near three- 



^-- 





hot feafoii', "great "plenty of juices are this way dif- 

 . V ,. charged and imbibed. Thus Manna is found to ex- 

 ,H";Jude [iVeat forth] from the Leaves of certain trees, if 

 ^^r^'cold night fliould follow a hot day j and the fame 

 j.;\"tl"iing frequently happens in divers other plants and 

 ,. trees, as we learn from the bees flying to the Lime- 

 tree, that they may gather that gumous fubftance from 

 their Leaves ; and it is from the furfaces of the 

 Leaves, '':^sv/ell as from the flowers, thofe animals 

 coUcSt'therrKoney -, but if the lieat fhould be lefs, 

 ailthe ruperfliiousliUmours, except thofe which, per- 

 haps, are tranfmitted by infenfible tranfpiration thro' 



So in this experiment, ' the Apples 'and Leaves im- 

 bibed four-fifths of an ounce, the Leaves alone near 

 three-fifths, but the two large Apples imbibed and 

 perfpired but one third part fo much as the twelve 

 Leaves, tlicn' the one Apple imbibed the one-fixth 

 part of what was' imbibed by the twelve Leaves ; 

 therefore two Leaves imbibe and perfpire as mucn 

 as one Apple; whence their perfpirarions feem to 

 be proporrinable to their furfaces, the furface of the 

 Apple being nearly equal to the fum of the upper 



and under furfaces of the two Leaves. 



Whence it is probable that the ufe of thefe Leaves 



(which are placed jufl: v;here the fruit joins to the 



tree} is to bring nourifliment to the fruit. ■ '^ 



> - 



'-' 



AnJ 



