PRO TOP LA SMIC MO VEMENT. 



8l 



nuclei. During the mitosis the surface extent of the proto- 

 plasmic area becomes greater, and the blastomeres, which had 

 become so flattened against each other that they were nearly 

 perfect hemispheres, again become more and more spherical in 

 shape ; at the same time currents seem to move outward from 



Fig. 5. 



Fig. 6. 



Figs. 5 and 6. — Entire eggs of C. plana, lateral and apical views. The centrospheres are shown 

 in light shading. The arrows indicate the directions of the protoplasmic movements. 



the centre of the ^g%, and this time in such direction as to 

 bring about a laeotropic shifting of the nuclei and protoplasmic 

 areas (Fig. 7). This movement continues until the anaphase 

 of the second cleavage, when again the cell currents move toward 

 the centre of the Qg^ (Fig. 8). The direction of these currents, 

 though nearly radial, is still slightly laeotropic in the two blasto- 



