IV. i INITIAL STRUCTURE OF THE GERM 167 



these two divisions the qualitatively distinct parts of the cyto- 

 plasm may be separated from one another in any assignable 

 manner, the nuclear material being distributed to these in any 

 assignable order. The symmetry of segmentation has no relation 



I 5 



90 -BO -TO -60 50 40 "30 -20 - K> 



\0 + 20 +30 +40 +50 +60 +70 +-80 4-90 



FIG. 81. Frequency polygon of the angle between the plane of 

 symmetry of the Frog's egg and the sagittal plane of the embryo. 

 n = 509, M= 2-23 -889, <r = 29-75 -629. 



either to the symmetry of the embryo or to the symmetry of the 

 undivided egg, for the first furrow tends to lie either in or at 

 right angles to the plane of symmetry and is not correlated with 

 it to any great extent l . The third furrow, however, being always 

 1 See, however, Appendix A. 



