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Show VEGETABLE PERSPIRATION. NoTE XXXIV. · 1 · 1 f n nd expofed long to the fun's light, becomes Oil clofe flnpped Ill a p lJa not u ' a . . . fl bl· . I f (! b the dccompofition of the water It conta li1S; the m amma e bleJched, as uppo ef, y J h 't l air uniting with the colouring matter of the air rifing above the fm ace, an t c vt a • 'I' d k d . · · ·k 1.1 1 t by {hutting up a phial of blc::~chcd 01 111 a ar rawer, 011, for 1t IS rcm a1 .au c, t Ja it in a little time becomes coloured again. . . . · · {1 the The followll1g expcnn1ent 1ews power of li •,ht in fepar:lti ng VItal all' from :::> • • •. ·mother bafis, V·I Z. f rom az, o t c. Mr . Sc. hede inverted a gl::lfs vcrTel filledf' wtth1 colouiie1f s • · ·d· ·no another al:.\fs contJin ing the C::une acid , and on expo 111g t 1~m to t 1e n1trousac1 11 o · . 1 • d 1 ·d tth r: 1 tl1e ·1 nvei·ted gl..tfs became partly filled w ll 1 pure atr, .a.n t 1e ac1 a e am: fun 's lig &t, fli 1 f 1 I I tn. ne became co 1o ure d . Sc· hc cJ e• 1· 11 Cer ll's 1\ nnal. 1-,: B6. . But d the ve e. o co our c ~ nitrous a ·Jd be qm·t e f tl 11 a.•J d (l oppel1' fo that no f:pa ce t.s left ' for the at r pro,lucedS to d itfclf into no change of colom t:Jkes pbce. Prtefll ey s Exp. VI. P· 34+· ee expan ' . . . 1· · Keir's ve~y excellent Chcmt c::tl D1.:.t10n. ry, P.· 99· new e, JllO.n. , . A rt un -fl ower t h ree f ee t a. t 1ct'&• a lf high 'a c-corduw"' to the cxp nme.n t of Dr. Hak.s , pet- fp·t red two pl·l lt~ ·1 11 one d a y (Vcab ctablt; S:,Jtiu; .) which is m::my ttmes as. mu..:h 1n p :·o- 1 . . porti·o n to l· i S 1r 111·f . te. e, as ·15 11erfJ1ired from the l'urfacc and lungs of ::t111ma l bo. •.tes ; Jt f·o llows t 1l :Jt t 1lC \'·J ta 1 a1· r J'It 1c- r,.1 tecl from the furface.s of. plants by the fun fh 1ne m. ufl: muc I1 exe c~: J t he qua nt .l•') ' of it abl.'> rbed by th-: ir refptratton, and that hence they tm-provet& l ea·t rm· w1l ·i C1 lt•'• ey J1' ,·c J urin(:l:'. the li o> ht 1n rt of the d. ay , and thus. blanched. ve-gctables .,, ill foo ner become tu1111etl info grem by the fun 's l1g!lt, th:m etiOlated :uwnal boclir::s will become tanned ye!hw by the f:~mc means. . . It is hence ev ident, that the curious clif-.:ovcry of Dr. Pnefllcy, that h1s green vegetab le matter and other aquatic plants gave out vital air when the fun fhone upon them, am I t I1 c 1c aves, of other plants did the f:·t me v. hen immerfed in . water., as. obferv~cl by Mr lngcnhouz, refer to the pel fpiration of Vt'getables not to their rerptratJOn, Becaufe Dr. rriellley obfe rved the pure air to come from both l}des of the leaves and even fJOm the ilalks of a water-flag, whereas ne fide of the leaf only Ccr\'es .t he office of lun~s , and certainly not the fl:alks. Expcr. on Air, Vol. lll. And thus 111 rcfpetl to the cm:umfl: ance in which pl.l.nts and animals fecmed the f.uthelt removed frum each otl.~er, I mean in their fuppofed mode of rcfpiration, by which one was beln:vcd tn punfy the air which the other had injured , they feem to difFer only in d grec, .1 . d the analogy between them remains unbroken. Plants are faid by many vvriters to grow much fafl:cr in the night th:lll in the clay; as is particularly obfervable in feedli nss at their ri ling out of the g:ound . T.his ~robably is a confcquence of th eir Deep ra tlt :.!r than of the abfwce of l1 ght; and 1n tillS I ft lppofe they alfo refemble animal bodies. 97 NOTE XXXV.~VEGETABLE PLACENTATION. While ill bright veins tbejilvery jap arcends C I U' • ANTO V.I. ·P9· AS buds are the viviparous offspring of vegetables 't b • . ' 1 ecomes neceiTary that they fhould be furndhed with placental velfels for their nour'fh 'II 1 . t ment, II t ley acqmre lungs or leaves for the purpofe of elaborating the common J, uices f th 1 • . The1re veffels exd. l . 0 e cart 1 mto nutnment m bulbs and in feeds and fupply th 1 · ' . . . . . ' . e young Pant Wtth a fweet juice tdl1t acquues leaves, as IS fecn 1n conv~rt1ng barley into It d . ma ' an appears from the fv. eet tafie of omons and potatoes, when they begin to grow. . The placental veffels belonging to the buds of trees are 1 d b h . P ace a out t e roots of molt, as the vtnc; fo m::tny roots are furnifl1ed with fwect or rnealy matt c . er as rern-root, bryony, carrot, turn1p, potatoe, or in the alburnum or fap-wood as in thofe tre h' h 1 • es w 1c proauce manna, wh1ch is depoftted about the month of Augufl: or 1'n th · · f li . . ' e JOIOts o ugar can.e, and graffes; early 111 the fpnng the abforbent mouths of thefe veffels drink up modlure from the earth, with a faccharine matter Jod aed cor that fi d · h • . • • b 1• purpo e unng t e ~re~e.dmg autumn~ an~ pufh thts nutnttve flu id up the veiTels of the alburnum to every wd1v1dual bud, as IS evmced by the experiments of Dr. Hales, and of Mr. Walker in the Edin~urgh P1.1ilofophical Tran~aEL The former obferved that the fap from the fiump of~ vme, wh1ch. he had cut off m the beginning of April, arofe twenty-one feet high in tubes affixed to It for that purpofe, but in a few weeks it ceafed to bleed at all, and Dr. Walker marked the progrcfs of the afcending fap, and found Jikewife that as foon as the leaves became expanded the fap ceafed to rife; the afcending juice of fame trees is fo copious and fo fw eet during the fap-feafon that it is ufed to make wine, as the birch, betula,_ and f~camore , acer pfeudo-platanus, and particularly the palm, and maple acer. Dunng thts afcent of the fap-juice each individual leaf-bud expands its new leaves, and fhoots down new roots, covering by their intertexture the old bark with a new one; and as foon as thefe new roots (or bark) are capable of abforbing fufficient juices from the earth for the fupport of each bud, and the new leaves are capable of performing their office of ex pofing thefe juices to the influence of the <1ir; the placental vcffels ceafe to aa, coalefce, and are transformed from fap-wood, or alburnum, into inert wood; ferving only for the fupport of the new tree, which grows over them. Thus from the pith of the new bud of the horfc-chefnut five veffels pafs out through ·the circle of the placental veffels above defcribed, and carry with them a minuter circle of thofe veffels; thefe five bundles of veiTels unite after their exit, and form the footfl: alk or petiole of the new five-fingered leaf, to be fpoken of hereafter. This f1ructure is well feen by cutting off a leaf of the horfe-chefnut (.IEfculus Hippocaftanum) in September before it fal!s, as the buds of this tree arc fo large that the flower may be fecn in them with the naked eye. N |
