ARBOR VITAE (Tree of Life), is a name applied to species of Thuja and Biota. The name was given by Clusius, and its origin is uncertain. The plants belong to the Coniferous order, and have been placed in the tribe Abietineae and the sub-tribe Cupressineae (Cypresses), in which the anthers are 3 to 5, rarely 2 ; scales of the cones 4 or more, usually placed opposite to each other in a decussate manner, persistent (not falling off), seeds having usually 2 to 3 wings; cotyledons 2. Thuja or Thuya occidentalis (L.), is the Western or American Arbor Vitae. The name Thuja seems to be derived from the Greek word (Mos, signifying sacrifice, probably because the resin procured from the plant was used as incense. The plant is the Cupressus Arbor Vito? of old authors. It is a native of North America, and ranges from Canada to the mountains of Virginia and Carolina. It is a moderate sized tree, and was introduced into Britain in 1596. In its native country it attains a height of about 50 feet. The leaves are small and imbricate, and are borne on flattened branches, which are apt to be mistaken for the leaves. When bruised the leaves give out an aromatic odour. The resin obtained from the plant has been used as a remedy in rheumatic affections. The flowers appear early in spring, and the fruit is ripened about the end of September. In Britain the plant is a hardy evergreen, and can only be looked upon as a large shrub or low tree. It does not furnish timber of good size. It is often cut so as to form hedges in gardens. The wood has been used for posts. Another species of Arbor Vitas is the Thuja orientalis (Linn.), Biota orientalis (Endlicher). The latter generic name is derived from the Greek adjective /3«DTOS, formed from Bios, life, probably in connection with the name " tree of life." This is the Eastern or Chinese Arbor Vitae. It is a native of Japan and China. It was introduced into France in the reign of Francis I. It has roundish cones, with numerous scales and wingless seeds. The leaves, which have a pungent aromatic odour, are said to yield a yellow dye. There are numerous varieties of this plant in cultiva- tion, one of the most remarkable of which is the Cupressus pendula of Thunberg. (J. H. B.)