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The Vegetation Book III, 

CHA Piso VL 
Of the Motions of Trunks. 
% HE Motions alfo of Truzxks are various. Princi- 
pally Fours fc. Afcending, Defcending, Horizontal, 
and Spiral. Thecaufe of the Afcent of a Plant, isa 
certain Maguetick Corre/pendence betwixt the Aer and 
the Aer-Veffels of a Plant; the Motion and Tendency 
whereof, the whole Plant follows. _ This I have af 
i, ferted, and I think, clearly demonftrated in my 
Firft and Second Wavks of the Avatomy of Plants. 1 will here add 
this plain Experiment. 
2. §. Take a Box of Moulds, with a hole bored in the bottom, 
wide enough to admit the Stalk ofa Plavt, and fet it upon ftilts half 
a yard or more above ground. ‘Then lodg in the Mould fome Plant, 
for Example a Beav, in fuch fort, that the Rost of the Bean ftanding 
in the Moulds may poynt upwards, the stalk towards the ground. 
As the Plant grows, it will follow, that at length the stalk will rife 
upward, and the Root, on the contrary, arch it felf downward. Which 
evidently fhews, That it is not fufficient, that the Root hath Earth to 
fhoot into, or that its Motiox is only an Appetite of being therein 
lodged, which way foever that be: but that its nature. is, though 
within the Earth already, yet to change its Pofition, and to move Down- 
wards, And fo likewife of the Trawk, that it rifes,when a Seed {prouts, 
out of the Ground, not meerly becaufe it hath an Appetite of being 
in the open Aer 5 for in this Experiment it is fo already; yet now makes 
a new Motiox upwards. 
3. §. BUT although the Natural Motion of the Trunk be to 
Afcend 5 yet is it forced oftentimes to Defcend. For the Trunk-Roots 
growing out of fome Plants near the ground, and fhrinking thereinto, 
like fo many Ropes, do pluck the Zrwxk annually lower and lower 
into the ground together with them; as may be feen in Scrophularia, 
Facobea, and many other Plants. 
4. §. IF thefe T7wzk-Roots break out only about the bottove of the 
Trunk, asin the aforefaid Plants, then the Trunk gradually Defcends 
into the Earth, andis turned into a Root, But if itbe very flender, and 
the Trunk-Roots break forth all along it, then it Creeps horizontally 5 
the faid Roots tethering it, as it trails along, to the ground ; as instraw- 
berry, Cinguefoyl, Mint, Scordium, &c. 
5. g. AS totheir Spiral Motion, it is to be noted; That the Wood 
of all Convolvula’s or Winders, ftands more clofe and round together in 
or near the Center, thereby making a round, and flender Truzk. To 
the end, it may be more tratable, to the power of the external Motor, 
He ever that bes and alfo more fecure from breaking by its winding 
otion. » 


