THE APPEARANCE OF HISTIOCYTES IN THE PERIPHERAL BLOOD

REVIEW OF THE LITERATURE  Although the histiocyte is occasionally seen in the peripheral blood, it is usually unrecognized, chiefly, it seems, because the existence of the cell in the circulation is not generally known. Therefore, it was felt that a review of the subject of the histiocyte and of its appearance in various clinical conditions might arouse more general interest in the appearance of the cell and its clinical significance. The name "histiocyte" signifies literally "tissue cell." It was first used in this connection by Aschoff¹ and Kiyono in 1913, and has come into use as the generic name for the cells of the reticulo-endothelial system. The word histiocyte has many synonyms: It is the macrophage of Metchnikoff² and of Evans,³ the clasmatocyte of Ranvier⁴ and of Sabin and Doan,⁵ the adventitial cell of Marchand,⁶ the pyrrole-blue celi of Goldmann,⁷ the hemohistioblast of Ferrata,⁸ the Ferrata the Ferrata various Italian