
Book III: of Trunks. i 17 
athwart one another; almoft like a Bewd, or fometimes, an entire 
or broken Saltyr inan Efeutcheo, In Oak, they make rather certain Typ, 34, 
Colunms, in the pofture of the Pale. And in Elw, they make, as it 38. 
were, many crofs Parcels, inthe pofture of the Fe/s, 
26. §. This great difference in the size and Pofition of the Aer 
Veffels, 10 the fame individual Plat, is one ground, for which, I think 
it probable, That there are divers Kinds of Aer-Veffels; as well as of 
Sap-Vefféls. Even asin Animals, there are divers Kinds of Organs for 
Spiration, and the feparation of Aer: Fifhes having their Branchie 
Land-Animats their Lungs; and thofe in Frogs, @c. being of a fome- 
what peculiar Kind. 
27. §. THE Form and Texture of thefe Feels, and the various 
ways whereby they may be beft obferved, 1 have already defcribed 
and fhewed in my Avatomy of Roots. As to their Form, onething P. 1.¢. 4. 
remarqued was this; That they are never Ramified, but diftinGly 
continued from one end of a Plant, {mall or great, to the other: 
as the Nerves are in Animals. A further and eafie proof whereof, 
may be made, only by holding up a piece of an ordinary. Cane, 
about } a foot long, cut very {mooth at both ends, againft a full 
light: whereupon, if you keep it in a ftraight Live betwixt the 
Light, and the caft of your Bye, and then look fteadily, you may 
fee quite through it, that is, through the Aer-Veféls, which run ftraight 
along the Cave from end to end. 
28. g. As to their Texture; whereas, oftentimes, the Aer-Veffels 
appear to be wzroaved in the form of a very {mall Plate, it is to be 
noted, That it is not only of different bredth, in divers Plavts, and 
ufually much broader inthe Root, than in the Travk: but alfo, that 
in the Truk, many times, the faid Vefels are unroaved or refolved; 
not inthe form of a Plate, but of a Round-Thred. The Caufes of 
which Diverfity, are principally. Three; wiz. The weftage of the 
Fibres of which the Aer-Vefféls confit; The deference betwixt the 
faid Fibres, or betwixt the Warp and the Woof; And the different 
Kinds of Woof. 
29. §. By the Weftage of the Fibres, it is, That the Vefels, of 
tentimes, uwroave in the form of a Plate. Asif we fhould imagine a 
piece of fine narrow Ribband, to be woun’d fpirally, and Edg to Edg; 
round about a Stick; and fo, the Stick being drawn out, the Rzb- 
band to be left in the Figure of a Tube, anfwerable to an Aer-Veffel, 
For that which, upon the w#roaving of the Vefél, feems to be a Plate, Tab. 39: 
or one fingle Piece, is, as it were; a Natural Ribband, confifting of 
feveral Pieces, that is, acertain number of Threds or ‘Round:Fibres, 
ftanding parallel, asthe Threds do in an Artificial Ribband. ‘And as 
in a Ribband, {0 here, the Fibres which make the Warp, and which are 
Spirally continu'd ; although they run parallel, yet are not coallefcents 
but conteined together, by other Tranfverfe Fébres in the place of 
a Woof. 
30. §. And as the faid Fibres are tran{verfly continued, thereby 
making a Warp and Woof: So are they (as in divers woven Manu- 
fadures ) of very different Bulk; thofe of the Former, being much 
bigger, and therefore much ftronger, than thofe of the Latter. By 
which means, as Cloth or silk will often Tear one way, and not ano- 
ther; {6 here, while the Warp or thofe Fébres which are Spirally oo 
tinued; 


































































