Abstract: A method for automatically classifying multi-parameter data into cluster groups for the purpose of defining different populations of particles in a sample by automatically defining a position of at least one variable position, geometric boundary surface on a two-dimensional scatter plot so as to enclose a group of the displayed particles in a data cluster; with the boundary surface having a polygonal shape defined by a plurality of vertices about at least one cell cluster created by building at least one histogram from cross sections of the two-dimensional scatter plot. Preferably, each cross section of the geometric boundary includes a rectangular, two dimensional gate. The method is particularly useful in the field of cellular analysis using, for example, flow cytometers wherein multi-parameter data is recorded for each cell that passes through an illumination and sensing region.

Abstract: Cells fixed with a fixative, reduced with a Schiff's base reducing agent and then dried in the presence of .alpha.-.alpha.-trehalose retain their light scatter and fluorescence properties and may be used, when rehydrated, as standards or controls in cellular analysis.