Book IIL of Trunks. 129 

C HAP TH, 
Of the Structure of the Parts. 
THIRD enquiry, is into the Generation and 
Strudure of Parts. The manner whereof I have 








feemeth to be proved, by the eafy slipping of the Barque of Willow, 
and moft other Trees, when full of Sap, from the Wood, 
2. §. But, notwithf{tanding this, they are as truly continuous, as 
the skin of the Body is with the Flefh: fc. by means of the Parenchy- 
mas, which is one entire Body, running from the Barque into the Wood, 
and fo uniting both together; as ina Brazch of Vine or Corin-Tree, 
when the Barqve is {tripped off, is apparent 5 the Spaces between the 
feveral Parts of the Wood, being filled up with the Parenchymous, infer- 
ted from the Barque. 
3. g. Now the reafon why the Bargue neverthelefs flips fo eafily 
from the Wood, is plain, viz. Becaufe moft of the young Veffels and Pa- 
venchymous Parts, are there every year fucceflively formed 5 that is, be- 
twixt the Wood and Barque : where the faid Parts newly formed, are 
as tender, as the tendereft Ve/éls in Animals. And we may imagine, 
how eafie it were at once to tear or break a thoufand Veffels or Fibres 
of an Ezbrio, of a Womb or Egg. 
4. §. THE fame Pefels of the Barque being always braced, and 
gradually falling off, together with the Parexchywa, into the utmoft 
Rind : Hence it is, that the Barques of many Trees, are asit were, lat- 744-19 
ticed with feveral Cracks of divers Sizes,and fometimes in the Figure of 
Rombs: the faid Fiffures veprefenting the. Poftion and Traé of the 
Veffels in their Braces. Hence alfo it is, that the Barque of fome Trees, 
as of Corin, Cherry, &c. falleth off in Rings, fc. becaufe the Sap-Veffels 
are pofited in the fame manner in the Barque. 
5. §. The Sap-Yeffls, as they are generated at the inner Verge of 
the Barque : fo likewife, in a {mall quantity, at the utmoft Verge of the 
Pith. Thefe being not only fed with a more vigorous Sap, but with 
great caution, fecured within the Wood, for the propagation of the 
fucceeding Buds. 
6. §. Hence alfo it is, that is, by the annual accretion of thefe ‘ 
Veffels,chat the Pith is fometimes lefs in the Trunk, than in the Branches; Tab. 18; 
and lefg in the elder Branches, than in the youugers and fometimes ‘tis 
allmoft wholly filled up, By which means, asthe Brawches carry every 
year a greater burthen; fothey become ftill more fturdy the better to 
fupport it. 
7. g§ SOMETIMES alfothe Pith breaks and fhrinks up, thus 
making the Trak a Pipe. The caufe whereof, is either the Largene/s 
f£ its Pores; or the Thinnefs of the Sides ae faid Pores; upon oa 
d which 
Tab. 19; 





































































