Abstract
Peripheral blood and bone marrow samples obtained from 22 children with acute lymphocytic leukemia in relapse and 24 children in remission were cultured in vitro by the double layer agar technique. A substantial difference between peripheral blood and bone marrow colony forming units (CFU) from patients in remission was noted, while in relapse the difference was variable. The majority of the bone marrow samples was diluted with peripheral blood, and a method was devised by which the corrected bone marrow CFU content can be calculated.