452 



GARY N. CALKINS 



%l %Z %3 VZA %5 Vz 



'26 



Fig. 1 Uroleptus mobilis in stage of conjugation similar to that of the pair 



from which series PXl was derived. The black line indicates the plane of cutting. 



Fig. 2 PXl series. Sketches of the living fragment on successive days during 



reorganization after cutting, from protocols. The vesicular area indicates 



the relative form and sizfe changes of the n'ew macronucleus. 



