308 



GENERAL MORPHOLOGY OF PLANTS 



474. The male plants and sperm cases (antheridia). The 

 sperm cases are borne on special outgrowths, the gamete bearer.* 

 These are disk-shaped and stalked. The sperm cases are in 

 flask-shaped cavities of the upper surface. Each sperm case is 



a more or less oval body like a 

 stalked capsule with a wall of a single 

 layer of cells. The interior is a mass 

 of minute cells in each of which two 

 sperms are formed. Each sperm is a 

 long, slender body, with two long, very 

 slender cilia which lash about and 

 cause it to move in the water. 



475. The female plant and egg 

 cases (archegonia) . The egg cases 

 or female organs are also borne on 

 special outgrowths, the gamete bearers. 

 The egg gamete bearer is shaped some- 

 thing like the sperm gamete bearer, 

 - 2g 3- but the disk is divided into slender 



Section of antheridium of Mar- 

 chantia, showing the groups of rays and 

 sperm mother cells. 



the stalk 



is longer, giving it an umbrella 

 shape (fig. 285). The egg cases 

 are borne on the under surface 

 of the disk, between the delicate, 

 thin, laminate tissues which hang 

 downward and protect them from 

 drying out. Each egg case is a 

 flask-shaped structure with a swol- 

 len base (venter), and a long, 

 slender neck with a canal leading F |!' 28 , 4 ' . 



Sperms of Marchantia uncoiling 



down to the egg in the basal part, and one extended, showing the two 

 30 ^ t cilia. 



When the egg is ripe the canal 



opens, and if a sperm enters and passes into the egg, it unites 



with the egg nucleus and fertilization results. 



* Gametophore, because it bears gametes. 



