43° 



Evolution and Adaptation 



equal parts, so that we find now three polar bodies and the 

 egg (Fig. 6 G). A strictly analogous process takes place 

 in the formation of the spermatozoa (Fig. 7 B-F). The 

 mother-cell of the spermatozoon divides into two parts, which 

 are equal in this case (Fig. 7 B-D). Each of these then 



6 x^ y H 



FIG. 6. — Diagram showing the maturation of the egg. 



divides again (Fig. 7 E, F), producing four cells that are 

 comparable to the three polar bodies and the mature egg. 

 Each of the four becomes a functional spermatozoon (Fig. 



7 G, H). Thus while in the maturation of the egg only the 

 egg itself is capable of development, in the case of the male 

 cells all four products of the two maturation divisions are 

 functional. 



