n6 Vegetable Staticks. 
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 
expanfion of feveral leaves ; 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 ceafc 
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, 
mod eafily feparates while it is lubricated 
with plenty of fap : But as foon as the leaves 
expand fufficiently to perfpire off plenty 
of fap, the bark will then no longer run (as 
they term it) but adheres mod firmly to 
the wood. 
Experiment XXXIX. 
In order to try if I could perceive the 
flem of the Vine dilate and contrad with 
heat or cold, wet or dry, a bleeding or not 
bleeding feafon, feme time in February , I 
fix'd to the flem of a Vine an inftrument in 
fuch 
