an auxiliary apparatus for a particle analyzer for measuring the particle count within particle size intervals bounded by shiftable or displaceable thresholds . infeed lines conduct the signals generated in a feeler to comparators . other infeed lines conduct the comparison voltages generated by comparison voltage generators to the same comparators , an operating element simultaneously alters the comparison voltages from two comparison voltage generators by the same magnitude and a selector switch connects one of two infeed lines with one of the infeed lines . the inputs of an antivalence or exclusive - or discriminator are connected by an infeed line or conductor with a time - delay element and by an infeed line or conductor with one comparator , the output of which discriminator is connected by a line or conductor with a pulse counter .