1. In the usual therapeutic dosage in mice with the Ak4 strain of leukemia, TEM caused a prolongation of survival time, held the total leukocyte count down at severely leukopenic levels, delayed the appearance of immature lymphocytes in the peripheral blood, and caused a marked delay in the appearance of leukemic infiltrations of the liver, spleen, bone marrow and kidney.
2. A single massive dose of TEM, administered on the seventh day of the disease when the total leukocyte count was high, caused a rapid fall in the count and depressed the number of prolymphocytes in the peripheral blood.
3. Single massive doses of such structurally related compounds as hexamethylene diethylenurea, 2,4-diethylenimino-6-amino-s-triazine, and to a lesser degree, 2-ethylenimino-4,6-dimethoxy-s-triazine caused a similar fall in the total leukocyte count when administered on the seventh day of the disease.