ii8 A TEXTBOOK OF THEORETICAL BOTANY 



mother cell. Each cell has a single nucleus and associated with it a red 

 pigmented eye spot. When mature a portion of the wall of the mother cell 

 dissolves, leaving a small pore through which the gamete is discharged. In 

 this process the flagella emerge first and show active movement, while the 

 contents of the cell are still emerging. 



The Female Gametangium 



Like the male, the female gametangia are scattered over the whole surface 

 of the female plant and may be developed alone or associated with hairs 

 (Fig. loo). These hairs may develop long before any evidence of the game- 



Female gamet- 

 angium 



Fig. ioo. — Cutleria multifida. Transverse section showing 

 structure of thallus and two clusters of female 

 gametangia. 



tangia is seen. Both the hairs and the gametangia arise from superficial 

 cells of the thallus, but usually the filaments are shorter and not so much 

 branched as in the male. The development of the gametangium is similar 

 to that of the male, but the number of mother cells produced is considerably 

 smaller. A mature female gametangium consists of from four to seven tiers, 

 each being composed of from four to eight cells. Thus from sixteen to about 

 fifty-six female gametes are ultimately liberated from each gametangium. 



The mature female gamete is an oval structure with two long flagella, 

 the longer one pointing forward and the other backwards, attached to its 

 side in the region of a red pigment eye spot. The gamete also contains 

 about thirty oval plastids. When first liberated it is actively motile but 

 it soon becomes sluggish, the shape becomes spherical and the flagella are 

 withdrawn. 



