34 
MEMOIR OP RAY, 
before the expansion of the leaves, it was clearly 
proved that the sap flows not only through the inner 
bark, but by all the pores of the wood; for the quan- 
tity of sap that issued was found to be in proportion 
to the' depth of the hole. “ To put it out of all 
doubt,” says Mr Ray, “we took away, on one side 
of a birch tree, bark and wood to a considerable 
depth, and bored an hole into the tree, where die 
piece was taken away; out of which hole it bled 
copiously, notwithstanding we carefully prevented 
any other sap coming on the filter, but what pro- 
ceeded from the hole .” The mucilaginous nature 
of the sap likewise attracted attention, and Ray in- 
geniously remarks, that “the white coagulum or. jelly 
which is precipitated, may be well conceived to be 
the part which every year, between bark and tree, 
turns to w r ood, and of which the leaves and fruit are 
made. And it seems to precipitate more when the 
tree is just ready to put out leaves, and begins to 
cease dropping, than at its first bleeding.” Experi- 
ments of a similar kind seem to have been continu- 
ed for several years, as we find frequent allusion 
made to them in Ray’s letters to Dr Lister and 
others of his correspondents. The results to which 
they led were communicated to the Royal Society, 
and subsequently published in the Philosophical 
Transactions. 
In his numerous journeys throughout almost every 
part of England and Wales, Ray had acquired, with 
that spirit of active enquiry which permitted the 
