86 



BIOLOGICAL LECTURES. 



Finally, I shall describe a few subdivisions of the first and 

 second quartettes with reference to these cell movements. 

 During and after the formation of the first quartette, the rota- 

 tions in these cells are dexiotropic ; when the nuclei have been 



FIG. 13. 



FIG. 14. 



FIGS. 13 AND 14. Entire eggs of C. plana. Fig. 13, Unequal division of first quartette cells. 

 Fig. 14, Subdivision of second quartette cells and formation of third quartette. 



