34 MEMOIE OF BAY. 



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 the 

 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 wood, 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 



