Abstract
Measurement is the backbone of science, and the science of hematology is no exception. For many years, the number of normal or abnormal cells in the blood and bone marrow has been determined by counting cells visually or electronically and identifying them by microscopical inspection. In biologic terms, these traditional methods have very limited sensitivity, but recently developed, more sensitive techniques are providing new information of theoretical and practical value. The report by Cavé et al. in this issue of the Journal 1 indicates the value of a molecular method of quantifying leukemic cells in patients with acute lymphoblastic leukemia (ALL) . . .