

The fcveral forts of Orpine may be eifily propagated 

 by cuttings during the fummer months, or by part- 

 ing of their roots either in fpring or autumn; thefe 

 thrive beft in a dry foil and a fliady fituation, but may 

 alfo be planted for the fame purpofes as the other forts, 

 efpecially the fixtecnth fort, which is evergreen. The 



' " ave a very good 

 effeft in rock-work, and the plants require no care ; 

 for when they are fixed in the place, they will fpread 

 and propagate fad enough. 



The ftalksof the common Orpine are frequently cut 

 in fummer, and failened to laths of the fize of chim- 

 ney-boards, which being framed together, are ufed 

 for fcreening tlie fight of the fire-grates in rooms ; 

 thefe {talks will Ihoot and fpread over the frame, and 

 if the frames are taken out once a week, and the 

 ftalks watered over to refrefh them, they will continue 

 in verdure for two months. 

 SEED: The Seed of a plant confifts of an embryo 

 with its coat or cover. The embryo, which contains 

 the whole plant in miniature, and which is called the 

 germ or bud, is rooted in the placenta or cotyledon, 

 which makes the coat or involucrum, and ferves the 



the chorion and 



I.e. 



fame purpofes as the fecundines, 

 amnis in animals. 



The placenta or cotyledon of a plant is always dou- 

 ble, and in the middle and common center of the two 

 is a point or fpeck, which is the embryo or plantule. 

 This plantule, being afted on and moved by the 

 warmth of the fun and the earth, begins to expand, 

 and protrudes or fhoots out its radicle or root both 

 upward and downward. By this it abforbs the nu- 

 tritious juice from the earth, and fo grows and in- 

 creafes, and therequifite heat continuing, the growth I cal, by the prefTure of the air. 



contraftion be promoted by the lencthcninfr of tl- 

 upper from the adlion of the fun ; t1ie conlcquencc 

 whereof will be, the roots recoiling, infinuating far 

 ther into the earth, and getting beneath the body of 

 the Seed. ^ 



In cf word : the earth draws the root toward itklf and 

 the fun promotes its defcent ; on the contrary,' the 

 fun draws up the plume, and the earth in fome mcL 

 fure, fends it towards the fame. 

 M. De la Hire accounts for the fame perpendiculari- 

 ty, by only conceiving the root to draw a coarfcr and 

 heavier juice, and the ftem a finer and more volatile 

 one. In the plantule therefore we may conceive a 

 point of feparation, fuch as, that all on one fide, e o- 

 the radial part is unfolded by the groffer j and all o^n 

 the other by more fubtile juices. 



If the plantule then be inverted, and the root a-top 

 as it ftiU imbibes the grofifer and heavier juices, and 

 the ftem the lighter ^ the point of feparation beincr 

 conceived as the fixed point of a lever, the root mull 

 defcend, and at the fame time that the volatile juices 

 imbibed by the ftem, tend to make it mount. Thus 

 is the little plant turned on its fixed point of feparation 

 till it be perfectly ereft. 



, M. Parent accounts for the 

 ftem's continuing to rife in the vertical diredion, thus: 

 the nutritious juice being arrived at the extremity of 

 a rifing ftalk, and there fixing into a vegetable fub- 

 ftance, the weight of the atmofphere mult determine 

 it to fix in a vertical pofition, fo that the ftalk will 

 have acquired a new part of perpendicularity over the 

 reft J juft as in a candle, which held any how oblique- 

 ly to the horizon, the flame v/ill ftill continue vertt- 

 cal, by the prefllire of the air. 

 The new drops of juice that fucceed, will follow the 



Thus, e. g. a Pea or Bean being committed to the I fame direftion 5 and as all tc^-ether form the ftem 



ground, isfirft found to cleave into two parts, which that muft of courfe be vertical,'^unlefs fome particular 



are, as it were, two leaves or lobes of the placenta^ and " r^ - 



in the fiflure appears a point, which fhoots out at foot 



downward, and a bud upward ; the firft fpreading it- 



felf in the foil to catch the moifture thereof, and the 



latter, mounting into the air> becomes the ftem or 



body of the new plant. 



contmues. 



circumftances intervene. 



And that, whereas tlie branches are Kkewifc obferved, 

 as much as poflible, to afFedperpendicularity in moft 

 inftances, infomuch, that though they be forced to 

 flioot out of the ftem horizontally, yet in their progrefs 

 ..,,-,_,. - . ^hey ere(5^ themfely^es; M. Parent folves this, from 



It is very remarkable how the plumule, or future ftem, j the vei-tical tendency of the nutritious juice, up the 

 fhould always get uppermoft, and the radicle or foot j ' ftem ; for the juice, being received in this diredion 

 be turned downward, and this too perpendicularly to j into the new tender buds, finds at firft little refiftance ; 

 the horizon ; and not only this, but if, by any exter- j and afterwards as the branch grows firmer, it furnilhes 

 nal means, the ftem be diverted from this perpendi- a longer arm of a lever to ad by. 

 culai, and bent, for inftance, toward the earth, in- Mr. Aftruc accounts for the perpendicular afcent of 

 ftead of perf-vering in that direftion, it makes an an- the ftem, and their redrefling themfelves when bent. 



gle or elbow, and redreffes itfelf. 



The fame is obferved in trees, &c. blown down, with' 



on thefe two principles. 



I. That the nutritious juke arifes from the root t^ 



their roots by the wind, or in thofe planted in pots, the top in longitudinal tubes, parallel to the fide of 



upon turning the pots upon one fide, ' ^' ^— ^ — li-i • . -it .^ n __ 



Now the Seed, from which a plant arifes, being the 

 plant Itfelf 



if it be depofited in the ground with the plumule 

 perpendicularly upward, and the radicle downward. 



A t? --- — ---_ — ^ — 



the plant, which communicates either by themfelves, 

 _ ., . , ^ - or by means of other horizontal tubes, proceeding 



in miniature, it is eafy to fuppofe that, [ from the circumference of the plant, and terminated 



in the pith. 



2. That fluids contained in tubes, either parallel or 





the difpofition ftiould be maintained in its future [ oblique to the horizon, gravitate on the lower part of 

 rvrntiri-K ■ thc tubes,' ahd not at all on tlie upper. 



From hence it eafily follws, that in a plant pofitcd 

 either obliquely or parallel to die horizon, the nutri- 

 tious juice will aft more on the lower part of the ca- 

 nals than the upper ; and by that means infinuate 

 more into the canals communicating therewith, and 

 be coUefted more copioufly therein ; thus the parts 

 on the lower fide will aft more on the lower part, and 

 will receive more accretion, and be more nourifhed 

 than thofe on the upper ; the confcquence whereof 

 muft be, that the extremity of the plant will be oblig- 

 ed to bend upward. 



The fame principle brings the feed into its due fitua- 

 tion at firft. In a Bean planted upfidc down, the 

 plume and radicle are eafily perceived with the naked 

 eye, to flioot at firft direftly for about an inch ^ but 

 thenceforth they begin to bend^ the one downward. 



growth. 



But it is known that Seeds, fown either of them- 

 selves, or by the help of man, fall at random, or 

 among an infinite number of fituations of the plumule, 

 &c. The perpendicular one upward is but one, fo 

 that in all the reft it is neceflaiy the ftem and root each 

 make a bend, to be able the one to emerge direftly 

 upwards, the other downward. Now what force is it 

 that,efFefts this change, which is certainly an aftion 

 of violence. ? 



Mr. Dodart, who firft took notice of the phasnome- 

 non, accounts for it by fuppofing the fibres of the 



■em of fuch a nature, as to contraft and (horten by 



he heat of the fun, and lengthen by the moifture of 

 the earth ; and on the contrary, the fibres of the root 

 to contraft by the moifture of the earth, and lengthen 

 by the heat of the fun. 



On this principle, when the plantule is inverted and I and the other upward. 

 the root a-top, the fibres of the root being unequal- 

 ly expofed to the moifture, viz. the lower parts more 

 than the ' ' *" - - 



upper 



-' 



contrad, 



The two placentute or cotyledons of a feed are, as it 

 were, a cafe to this little tender plantule or point, co- 

 vering it up, Iheltering it from injuries, and feeding 



