SEARCH Articles Figures Tables A living primary spermatocyte of the crane fly Pales ferruginea seen by phase contrast microscopy during prometaphase. Characteristic congressional motions are shown by the three bivalents one of these is marked by arrows at its approximate midpoint for ease in following its motion first to the equator and on toward the upper pole and then back toward the lower pole with achievement of the final, equatorial position. The time in hours and minutes is indicated on each print. XI,440. From Dietz. 969. Naturwissenschaften, 56 [Publishers Imprint]