a 
Book Wit oP Tah 127 

Ors at: Om aan A 8 
Of the Motion and Courfe of the Aer. 


a NS E NEXT enquiry to be made, is, into the 
cox a \) Motion and Courfe of the Aer. Where this 
Bia We ee™ queltion will firft of all be asked 3 fe. Which way 
RAeeSecy the Aer firlt enters the Plant; whether at the 
Trunk, Leaves, and other Parts above ground ; 
Su) orat the Root > Ianfwer, That it enters in part, 
OM at them all. For the Reception, as well as Extra- 
: milfion whereof, the Pores are fo very large, in 
the Trunks of fome Plants, asin the better fort 
of thick walking Caves, that they are vifible, to a good Eye, with- 
outa Glafs; but with a Glaf, the Cane feems, asif it were ftuck top Tab, 19. 
fall of holes with great Pixs: being fo large, asvery well to refem- 
i the Pores of the Skiz in the end of the Fingers and Ball of the 
land. . 
2. §. Inthe Leaves of Pize, they are likewife through a Glajs, a 
very Elegant Show ; ftanding all moft exa@ly, in ravk and file, 
throughout the length of the Leaves. The Figure whereof fhall be 
given hereafter, when we come to the Anatomy of the Leaf. 
3- §. But although the der enters, in part, at the Trvzkand other 
Parts, efpecially in fome Plants; yet its chief entrance, is at the 
Root. Evenas {ome Parts of Aer, may continually pafs into the Body 
and Blood, by the Habit, or Pores of the Skins but the chief entrance 
hereof, is at the Mouth. And what the Adonth is, to an Avimal 5 that 
the Root isto a Plant. ; : 
4. §. Again,if the chief entrance of the Aer,were at the Trunk; then; 
before it could be mixed with the sap in the Root, it muft defcend ; 
and {o move not only contrary to its own Nature, but likewife in a 
contrary Courfe to the Sap, throughout the Plaxt. Whereas, by its 
Reception at the Root, and {o its Tranfition from thence ; it hath a more 
natural and eafie motion of Afcent. For while the sap afcends, that 
the Aer, in the fame Plazt, fhould continually defcend, cannot reafo« 
nably be fuppofed. 3 
5. §. The fame is further argued, Fromi the fewnefs and {mall- 
nefs of the Diametral Portions in the Trunk in comparifon with thofe 
in the Root. In which Nature hath plainly defigned the fame, for the 
Separation of the Aer from the Sap,after they are both together received 
thereinto. So that the Reception and Courfe of the Aer, is made on this 
manner following. 
6. § THE Aer beinga springy Body, it infinuates into all the 
Holes and Cranies of the Earth; and {o is plentifully mixed therewith. 
Whereupon, asthe Sap enters the Roct, more or lefs Aer {till intrudes 
it felf together withit. The Liguid Portion of the sap, fwells and 
fills up the Succulent Parts of the Barque. The Aery Part, is, as was 
faid; feparated from the Liquid, into the Diarsetral Portions, Which 
running: 
































































