Plants are said by many writers to grow much faster in the night than in the day; as is particularly observable in seedlings at their rising out of the ground. This probably is a consequence of their sleep rather than of the absence of light; and in this I suppose they also resemble animal bodies. NOTE XXXV.--VEGETABLE PLACENTATION. _While in bright veins the silvery sap ascends. CANTO IV. l. 419. As buds are the viviparous offspring of vegetables, it becomes necessary that they should be furnished with placental vessels for their nourishment, till they acquire lungs or leaves for the purpose of elaborating the common juices of the earth into nutriment. These vessels exist in bulbs and in seeds, and supply the young plant with a sweet juice till it acquires leaves, as is seen in converting barley into malt, and appears from the sweet taste of onions and potatoes, when they begin to grow. The placental vessels belonging to the buds of trees are placed about the roots of most, as the vine; so many roots are furnished with sweet or mealy matter as fern-root, bryony, carrot, turnip, potatoe, or in the alburnum or sap-wood as in those trees which produce manna, which is deposited about the month of August, or in the joints of sugar cane, and grasses; early in the spring the absorbent mouths of these vessels drink up moisture from the earth, with a saccharine matter lodged for that purpose during the preceding autumn, and push this nutritive fluid up the vessels of the alburnum to every individual bud, as is evinced by the experiments of Dr. Hales, and of Mr. Walker in the Edinburgh Philosophical Transact. The former observed that the sap from the stump of a vine, which he had cut off in the beginning of April, arose twenty- one feet high in tubes affixed to it for that purpose, but in a few weeks it ceased to bleed at all, and Dr. Walker marked the progress of the ascending sap, and found likewise that as soon as the leaves became expanded the sap ceased to rise; the ascending juice of some trees is so copious and so sweet during the sap-season that it is used to make wine, as the birch, betula, and sycamore, acer pseudo-platinus, and particularly the palm. During this ascent of the sap-juice each individual leaf-bud expands its new leaves, and shoots down new roots, covering by their intertexture the old bark with a new one; and as soon as these new roots (or bark) are capable of absorbing sufficient juices from the earth for the support of each bud, and the new leaves are capable of performing their office of exposing these juices to the influence of the air; the placental vessels cease to act, coalesce, and are transformed from sap- wood, or alburnum, into inert wood; serving only for the support of the new tree, which grows over them.