MEMOIR OF RAY. 
33 
m the British Museum) contributed so essentially 
to the progress of natural history ; and, at a later 
period, Dr Derham, the learned and eloquent author 
of the Pkysico and Astro- Theology. He was like- 
wise solicited to become a member of the Royal 
Society, an institution recently established, but 
which had already done much in diffusing a taste 
for the physical sciences, and had given a powerful 
impulse to the study of natural history. He was 
admitted on the 7th November 1667, and several 
papers from his pen afterwards appeared in the So- 
ciety’s Transactions. 
The description and classification of vegetables 
were not the only departments of botany that re- 
ceived illustration from Ray’s labours ; he likewise 
ascertained some important facts in their physiolo- 
gy. The theory of vegetation was at this time very 
imperfectly understood, and every observation found- 
ed on careful experiment possessed of value. The 
accurate investigations of Grew and Malpighi were 
destined, soon after, to throw a powerful light on 
this difficult and interesting subject. In the spring 
of 1669, Ray availed himself of the privileged se- 
clusion of Middleton-Hall, and the observational 
powers and co-operation of its amiable proprietor, 
to institute a series of experiments on the motion 
of the sap in trees. The object was to ascertain 
the manner in which the sap ascends, and whether 
it likewise flows through the woody part of the tree. 
By boring holes of different depth into the trunk 
