LIVER WOR TS : MARCH A N TIA. 



227 



midrib, as shown in figs. 257, 261. The growing point of the 

 thallus is situated in the little depression at the free end. If we 

 examine the upper surface with a hand 

 lens we see diamond-shaped areas, and 

 at the center of each of these areas are 

 the openings known as the stomates. 



484. Antheridial plants. One of 

 the male plants is figured at 257. It 

 bears curious structures, 

 each held aloft by a short 

 stalk. These are the an- 

 theridial recep- 

 tacles (or male 

 gametophores). 

 Each one is cir- 

 cular, thick, and 

 shaped some- Fig. 257. 



what like a. bl* Male plant of marchantia bearing antheridiophores. 



convex lens. The upper surface is marked by radiating fur- 

 rows, and the margin is crenate. Then we note, on careful 

 examination of the upper surface, that there are numerous minute 

 openings. If we make a thin section of this structure perpen- 



Fig. 258. 



Section of antheridial receptacle from male plant of Marchantia polymorpha, showing 

 cavities where the antheridia are borne. 



dicular to its surface we shall be able to unravel the mystery of 

 its interior. Here we see, as shown in fig. 258, that each one 

 of these little openings on the surface is an entrance to quite 



