THE CARRIERS OF THE HERITAGE 23 



geometric progression throughout subsequent genera- 

 tions. In 1883, too late for Darwin to learn of it, 

 van Beneden discovered the important fact that the 



Primordial Sex Ceils 



V 



Manvj similar cell divisions 



Maturation ^ 

 — — = — =\^ 



Sperinatocyte 1- OocijU 

 Spermatids 2.-Oocijte 



V 



'^bortiva E^* 



Fig. 14. — Scheme to illustrate maturation of germ-cells. 



mature germ-cells, as expected, actually contain only 

 half the normal number of chromosomes. 



The mature egg- or sperm-cell, with half its normal 

 number of chromosomes, is termed a gamete (marry- 



