Vegetable Statkks. 119 
fpirations of trees, (hewn in the firft chapter) 
that the fall of the fap, in thefe fap gages, 
in the middle of the day, efpecialJy in the 
warmer days, is owing to the then greater 
perfpiration of the branches, which perfpi- 
ration decrcafes, as the heat decreafes to- 
wards evening, and probably wholly ceafes 
when the dews fall. 
But when towards the latter end of April ^ 
the fpring advances, and many young (hoots 
are come forth, and the furface of the Vine 
is greatly increafed, and enlarged by the 
cxpanfion of feveral leaves 5 whereby the 
perfpiration is much increafed, and the fap 
more plentifully exhaufted, it then ceafes to 
flow in a vifible manner, till the return of 
the following fpring. 
And as in the Vine, fo is the cafe the 
fame in all the bleeding trees, which ceafe 
bleeding as foon as the young leaves begin to 
expand enough, to perfpire plentifully, and 
to draw off the redundant fap. Thus the bark 
of Oaks and many other trees moft eafily fe- 
parates, while it is lubricated with plenty of 
fap : But as foon as the leaves expand fufHci- 
cntly to perfpire off plenty of fap, the bark 
will then no longer run (as they term it) but 
adheres moft firmly to the wood. 
I 4 Ex- 
