The mediastinal, lympho-epithelial organ was termed thymus to denote a ductless, gland-like body which has the appearance of a "warty excrescence" (Greek, thymos). Early investigators had ascribed a functional role to this gland including the production of humoral factors which modulated cell growth, maturation and exerted influence on the process of mineralization. Investigators of the past decade have vindicated these observations and identified that the thymus is, indeed, an organ which "sets in motion, and spurs on" (Gr. hormaein) target tissues.