The glycogen content of the lymphocytes of 44 cases of various lymphocytic proliferations was studied using a semiquantitative cytochemical technic. The lymphocytes of chronic lymphocytic leukemia and of lymphosarcoma (with one exception) showed greatly increased glycogen content. In acute lymphocytic leukemia and in one case of lymphosarcoma the glycogen content was low. The presence or absence of lymphosarcoma cells in the peripheral blood in cases of lymphosarcoma made no difference in the total score. The difference between the glycogen-positive "lymphosarcoma cell" and the glycogen-negative lymphoblast is apparently due to the greater maturity of the cytoplasm of the lymphosarcoma cell (which results from an asynchronism of nucleocytoplasmic maturation) and immaturity of the cytoplasm of the lymphoblast.
Three cases of benign lymphocytosis with atypical lymphocytes in the peripheral blood gave increased values. One case with atypical lymphocytes had normal values and two cases of lymphocytosis with morphologically normal lymphocytes also had normal values. It is concluded that the increase of glycogen in lymphocytic cells is due to an over-all proliferation of the lymphocytes and is not necessarily related to malignancy per se.