The sap ascends through the cellular and woody tissue, especially in the layers of wood not more than two years old. The hard heartwood does not convey sap, but in some trees, like the poplar, sap moves in the very centre. The elaborated sap returns from the leaves in a slow stream, through the delicate cellular structures of the bark, right down to the root, giving rise to the cambium layer, from the inner surface of which the annual layer of young wood is formed. At this time Ray began to prepare for the press his “Collection of Proverbs,” a curious book in its way, by which he is perhaps better known to the generality of his countrymen, than by any other of his literary labours. The first edition was published in 1672, but the work was subsequently much enlarged, and the author may almost be said to have exhausted his subject. From its very nature, delicacy and refinement had often to be dispensed with, but this is evidently not the fault or the aim of the writer. His learning and critical acuteness diffuse light over the whole, and make us overlook the coarse vehicle of our instruction. The first edition of the “Catalogue of English Plants,” already mentioned, came out in 1670, and the second in 1677. Their great author gave his work to the world with that diffidence for which he alone, perhaps, could perceive any just foundation. It was a wonderful book, considering that there was no recognized authority to help the author, who, seeing that there must be some real method in nature, strove to arrange or classify plants by the similarity or dissimilarity of those structures which were of the greatest importance. About this period the health of Mr. Ray seems to have been considerably impaired. He refused a tempting offer to travel again on the Continent, as tutor to three young noblemen; nor could the powerful attractions of Alpine botany, which was then to be studied, overcome that reluctance to leaving home, which arose from a feeble state of body. Indeed, this very reluctance or listlessness is accounted for by the turn which his disorder took, as it terminated in the jaundice. After this depressing complaint had left him, Ray resumed his botanical travels at home with fresh alacrity, visiting the rich stores of the north of England, with a companion named Thomas Willisel, whose name and discoveries he subsequently gratefully commemorated on many occasions. Nothing forms a more striking feature in Ray’s character than the unreserved and abundant commendation which he always gave to his friends and fellow-labourers. Then unfortunately an event occurred which called forth his affectionate feelings. On the 3rd of July, 1672, Mr. Willughby was unexpectedly carried off by an acute disorder, in the thirty-seventh year of his age. The care of his two infant sons was confided by himself to Mr. Ray, who was also appointed one of his five executors, and to whom he left an annuity of sixty pounds for life. The