20 



HEREDITY AND SELECTION IN SOCIOLOGY 



nucleus is again halved, two additional chromosomes being 

 ejected, and forming the second polar body (E). MeanwhUe 

 the first polar body divides into two, each with two chromosomes. 

 Thus there are eventually four nuclei produced from the original 



2nd Div. 



Fig. 2. — MATrEATiON of Ovum oe Egg-Cell (after Wbismann). 

 {By permission of Mr. Edward Arnold.) 



A, The primitive germ-ceU (cAr = chromosomes). B, the ovocyte, with 

 doubled chromosomes. C, first karyokinesis. D, immediately 

 afterwards, half the chromosomes (4) in the first polar body {pg). 

 E, second karyokinesis, first polar body [pg) divided, nucleus 

 effecting new division. E, the mature ovum, with two chromo- 

 somes ; three polar bodies outside the cell. 



ovocyte — namely, three polar bodies and the reduced nucleus 

 of the ovum — and each of the four nuclei has two chromosomes 

 — half the normal number. 



The chief interest of this complicated maturation process 



