28 



SEX AND HEREDITY 



(Fig. 15). The stamens produce pollen-grains. But these 

 are not themselves gametes ; the grains after transfer to 

 the leceptive part of the carpel, which is called the stigma, 

 germinate, and each forms a pollen-tube. Within this 

 two cells are produced which are the male gametes them- 

 selves (Fig. 16, A). The female gametes are formed 



FIG. 15. 



Flower of the Quince, in median section, showing the sepals (sep), petals (pet), 

 stamens (st), and carpels (c). The ovary (ov.) contains the ovules. (After Church.) 



within the carpels, which occupy the centre of the flower. 

 Each carpel encloses one or more ovules which develop 

 into seeds. The young peas within a pea-pod are familiar 

 examples of such ovules covered in by the carpellary leaf. 

 Deeply seated within each ovule is a single egg. This is 

 the female gamete, which is to be fertilized by one of the 

 male gametes (Fig. 16, B). At the moment we need not 

 consider the mechanism by which the junction of these 



