cambium, n. [LL. cambium exchange, fr. L. cambire to exchange. It was supposed that cambium was sap changing into wood.].
A series of formative cells lying outside of the wood proper and inside of the inner bark. The growth of new wood takes place in the cambium, which is very soft. [1913 Webster]
A fancied nutritive juice, formerly supposed to originate in the blood, to repair losses of the system, and to promote its increase. Dunglison. [1913 Webster]