Abstract
The leucocytes of the blood of normal individuals and of patients showing a marked polymorphonuclear leucocytosis contain enzymes capable of digesting coagulated blood serum in neutral, alkaline or acid solutions. The cells in pus that is composed principally of polymorphonuclear leucocytes and the leucocytes of the circulating blood in myelogeneous leukaemia contain similar proteolytic enzymes, which act best when the reaction is alkaline. The leucocytes of the circulating blood and of the enlarged lymph nodes from a case of large cell, acute, lymphatic leukaemia contain proteolytic enzymes that act qualitatively in much the same way as the leucocytes of pus and as the white corpuscles of the blood in myelogenous leukaemia. These large lymphocytes in acute lymphatic leukaemia can be differentiated biologically from the small lymphocytes in chronic lymphatic leukaemia which possess no proteolytic enzymes, and from the large endothelioid cells of the hyperplastic lymph glands which are proteolytic only in the presence of acid. These results seem to show that the large cells of the so-called acute lymphatic leukaemia are not true lymphocytes, but are nearly related to the granular myelocytes and should probably be considered as the forerunners to these cells.