Abstract
To understand the basic events during the passage of particles through the Coulter orifice, three experiments were performed. (1) The denpendence of the volume results on the particle path has been shown by ink-colored particle beams. (2) The deformation and alignment of cells during their passage through the orifice have been photographed by a nano-second photographing technique. (3) The absolute volume evaluation of particles has been studied with model particles in enlarged model orifices of different lengths. A new compact sizing instrument, "Metricell," equipped with a particle-independent electrical calibrating system, is described.