Abstract
The white blood cells of normal persons have been the subject of many and varied forms of investigation since they were first described in 1777 by Hewson.1 As a consequence, limits of normal have been established both for the total numbers per cubic millimeter of circulating blood and for the percentages of the types of cells comprising this total. These normal limits have been determined from observations made once on each of a group of healthy persons or from data obtained by repeated observations of the same person's blood over a period of hours. The influence of various physiologic processes on the white blood cell picture has also been studied extensively. However, comparatively little information is available concerning the fluctuations of the nucleated blood cells that may occur over an extended period of time in a normal person. Such observations as have been made appear not to have been conducted