A new flow cytometric pulse height analyzer offering microprocessor controlled data acquisition and statistical analysis.

The instrument described is capable of storing up to 112 one parameter histograms (128 channels) or 16 one parameter and 3 two parameter histograms (64 X 64 channels). A low cost 10 Mhz oscilloscope displays the graphical and alphanumerical data. During data acquisition, the original pulses, an analogue rate meter and the growing histogram are displayed simultaneously on the screen. The instrument may be completely operated by an 18 element keyboard. The data processor allows calculation of integrals, mean values, standard deviations and coefficients of variation of operator selectable regions of the acquired histograms. Gaussian distributions determined by the statistical parameters may be compared directly with the measured distributions. Distribution curves can be normalized, shifted, added, subtracted or compared with artificial distributions which are generated by superimposition of distinct Gaussian curves. Exponentially fitted background curves can be subtracted from the measured histograms. A text line at the top of the screen displays the numerical values and explanatory remarks. The two parameter histograms may be rotated, observed from the sides or back and projected either on the x- or y-axes. The projections or selected lines or columns can be transferred to the one parameter range and treated statistically. Sequences of one parameter distributions may be transferred two parameter range and displayed as pseudo-two-parameter histograms.