light; which at the fame time that it heats, doth wonderfully rarefy and raise the fap; till it perfpires and forms an atmosphere, like the effluvia of animal bodies. And though the leaves are fuppofed to perform principally the office of lungs, breathing out excrementitious vapours, and drawing in alimentary; yet it feems probable, that the reciprocal actions of repulfion and attraction are performed all over the furface of vegetables, as well as animals. In which reciprocation, Hippocrates fuppofeth the manner of nature's acting, for the nourishment and health of animal bodies, chiefly to confift. And, indeed, what share of a plant's nourishment is drawn through the leaves and bark, from that ambient heterogeneous fluid called air, is not easy to fay. It feems very confiderable and altogether neceffary, as well to vegetable as animal life.

34. It is an opinion received by many, that the fap circulates in plants as the blood in animals: that it afcends through capillary arteries in the trunk, into which are inofculated other veffels of the bark anfwering to veins, which bring back to the root the remainder of the fap, over and above what had been depofited, during it's afcent by the arterial veffels, and fecreted for the feveral ufes of the vegetable throughout all it's parts, ftem, branches, leaves, flowers, and fruit. Others deny this circulation, and affirm that the fap doth not return through the bark veffels. It is nevertheless agreed by all, that there are afcending and defcending juices; while fome will have the afcent and defcent to be a circulation of the fame juices through different veffels: others will have the afcending juice to be one fort attracted by the root, and the defcending another imbibed by the leaves, or extremities of the branches: laftly, others think that C

the

the fame juice, as it is rarefied or c heat or cold, rifes and fubfides in th I fhall not take upon me to decide this Only I cannot help obferving, that t gument from analogy between plants lofeth much of it's force, if it be co the fuppofed circulating of the fap, or lacteals through the arteries, and ing, by inofculations, through the v veffels to the root or lacteals again, conformable or analogous to the circ blood.

35. It is fufficient to obferve, wha knowledge, that a plant or tree is a complicated machine (a); by the fev motions whereof, the crude juices adm the abforbent veffels, whether of the or branches, are varioufly mixed, fep ed, digested, and exalted in a ve manner. The juice as it paffeth in and down, through tubes of diffe fhapes, and fizes, and is affected by compreffion and expanfion of elaftic viciffitudes of feafons, the changes of the various action of the folar light more and more elaborate,

36. There is therefore no chemistr nature, which addeth to the force of delicate, various, and artificial percolat inceffant action of the fun upon th air, earth, and water, and on all f bodies, animal, vegetable and foffil to perform all forts of chemical operati it fhould follow, that the air conta chemic productions, the vapours, fum (b) 29.

(a 30, 31:

and fpirits of all the bodies we know from which general aggregate or mafs, thofe that are proper being drawn in, through the fine veffels of the leaves, branches, and item of the tree, undergo in it's various organs, new alterations, fecretions, and digeftions, till fuch time as they affume the moft elaborate form.

37. Nor is it to be wondered, that the peculiar texture of each plant or tree, co-operating with the folar fire and pre-exifting juices, fhould fo alter the fine nourishment drawn from earth and air (a), as to produce various fpecific qualities of great efficacy in medicine: efpecially if it be confidered that in the opinion of learned men, there is an influence on plants derived from the fun, befides it's mere heat. Certainly doctor Grew, that curious anatomift of plants, holds the folar influence to differ from that of a mere culinary fire, otherwife than by being only a more temperate and equal heat.

38. The alimentary juice taken into the lacteals, if I may fo fay, of animals or vegetables, confifts of oily, aqueous, and faline particles, which being diffolved, volatilifed, and diverfly agitated, part thereof is fpent and exhaled into the air; and that part which remains is by the economy of the plant, and action of the fun, ftrained, purified, concocted, and ripened into an infpiffated oil or balfam, and depofited in certain cells placed chiefly in the bark, which is thought to anfwer the panniculus adipofus in animals, defending trees from the weather, and, when in fufficient quantity, rendering them evergreen. This balfam, weeping or fweating through the bark, hardens into refin; and this moft copioufly in the feveral fpecies of pines and

firs, whofe oil being in greater quantity tenacious of the acid fpirit or vegetal perhaps it may not improperly be calle action of the fun, and attracting the fu thereby exalted and enriched, fo as most noble medicine; fuch is the laft tree, perfectly maturated by time and f

39. It is remarked by Theophraft plants and trees while they put fort humour, but when they have ceafed and bear, then the humour is ftronge fheweth the nature of the plant, and fore, trees yielding refin fhould be cu mination. It feems alfo very reafona pofe the juice of old trees, whofe orga new fap, fhould be better ripened t others,

40. The aromatic flavours of veg to depend upon the fun's light, as muc As in the production of the later, th powers of the object, fo in that of the attractive and organical powers co-operate with the fun (a). And Ifaac Newton's experiments it appears, lours are virtually in the white light and fhew themselves when the rays a by the attracting and repelling powers even fo the specific qualities of the ela of plants, feem to be virtually or emine ed in the folar light, and are actual upon the feparation of the rays, by powers of the capillary organs in ve tracting and imbibing certain rays, w certain flavours and qualities, in like certain rays, being reflected, produce lours,

La (a) 36, 37.

more

(as s the

s, is

Ome a

Et of a

at all

e moft

minate

moft

there

er ger

o fup

ing no that of

s feem:

colours.

flecting former,

e plant

om Sir

all co

he fun,

parated

objects,

e juices Containxhibited peculiar

les, at

produce

nner as cain co

41.8

41. It hath been obferved by fome curious anatomifts, that the fecretory veffels in the glands of animal bodies are lined with a fine down, which in different glands is of different colours. And it is thought, that each particular down, being originally imbued with it's own proper juice, attracts none but that fort; by which means fo many various juices are fecreted in different parts of the body. And perhaps there may be fomething analogous to this, in the fine abforbent veffels of plants, which may co-operate towards producing that endlefs variety of juices, elaborated in plants from the fame earth and air.

42. The balfam or effential oil of vegetables
contains a fpirit, wherein confift the fpecific quali-
ties, the fmell and tafte of the plant. Boerhaave
holds the native prefiding fpirit to be neither oil,
falt, earth, or water; but fomewhat too fine and
fubtile to be caught alone and rendered vifible to
the eye. This when fuffered to fly off, for in-
stance, from the oil of rofemary, leaves it deftitute
of all flavour. This fpark of life, this spirit or foul,
if we may fo fay, of the vegetable departs without
any
fenfible diminution of the oil or water wherein it
was lodged.

43. It fhould feem that the forms, fouls, or
principles of vegetable life, fubfift in the light or
folar emanation (a), which in refpect of the ma-
crocofm is what the animal fpirit is to the micro-
cofm; the interior tegument, the fubtile inftru-
ment and vehicle of power. No wonder then that
the ens primum or fcintilla fpirituofa, as it is call-
ed, of plants fhould be a thing fo fine and fuga-
cious as to escape our niceft fearch. It is evident
that nature at the fun's approach vegetates; and

(a) 40.

languishes

பவது