154 c - M - CHILD. 



Plate IV. 



Figs. 15, 16 and 17. Early stages of first cleavage, showing distinct paternal and 

 maternal groups of chromosomes, in Fig. 17 both within a single nucleus. 

 Figs. 18, 19 and 20. First cleavage, with chromosomes in a single group. 

 The figures show wide variation in the orientation of the first cleavage spindle. 



