MEMOIR OF RAY. 33 



in 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 Physico 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 



