practical discipline in observation and experience. His first botanical works assumed the humble form of alphabetical catalogues. His and Mr. Willughby’s labours in the service of Bishop Wilkins were, indeed, of a systematical description, and accordingly the authors themselves were probably more dissatisfied than any other persons with their performance. They relaxed from these labours in a tour of practical observation through the west of England, as far as the Land’s End, in the summer of 1667, and returning by London, Mr. Ray was solicited to become a Fellow of the Royal Society, into which learned body he was admitted November 7th. Being now requested by his friend Wilkins to translate his celebrated work, “An Essay towards a Real Character and a Philosophical Language,” into Latin, he undertook, and by degrees accomplished, that arduous performance. The following summer was agreeably spent in visits to various literary friends, and in a solitary journey to the north. His former companion, Willughby, being just married, stayed at home; but Ray joined him in September, 1668, and remained for most part of the ensuing winter and spring. The seclusion and leisure of the country, with the converse and assistance of such a friend, were favourable to the prosecution of a new subject of inquiry, which now strongly attracted the attention of our great naturalist—the theory of vegetation. The first step of the two philosophers in this little-explored path was an examination of the motion of the sap in trees; and the result of their inquiries, communicated to the Royal Society, appeared soon after in the “Philosophical Transactions.” Their experiments clearly prove the ascent of the sap through the woody part of the tree, which is easily detected by boring the trunks at different depths before their leaves are unfolded; and they observed, also, the mucilaginous nature of the flowing sap, “precipitating a kind of white coagulum or jelly, which,” says Ray, in a note preserved by Derham, “may be well conceived to be the part, which every year, between bark and tree turns to wood, and of which the leaves and fruits 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.” The accuracy of the leading facts recorded by these ingenious men is confirmed by subsequent observers, who have further pursued the same subject, which is now sufficiently well understood. The sap originates in the liquid matters which are absorbed by the roots of plants; they enter the minute cells of the ends of the roots and permeate the cellular tissue. This sap ascends in the plant, assisted by the evaporation from the leaves. The sap ascends with considerable rapidity to the leaves, where it is subject to changes, the result of physiological action. It descends from the leaves, having had its chemical constitution altered, and is fit for the nutrition of the plant.