404 A TEXTBOOK OF THEORETICAL BOTANY 



which represent the apices of a corresponding number of branches. This 

 disc has all the features of the anatomical structure of the thallus. There 



Pore 



Assimilating 

 chamber 



Rhizoids 



Fig. 386; — Marchantia polymorpha. Antheridiophore, 

 transverse section of stalk showing thalloid structure. 



is the same type of epidermis with its ventilating pores and the same 



large chambers containing assimilatory filaments ; amphigastria are present, 



and rhizoids are given off from the lower surface and pass downwards 



through the channels of the stalk. The 



antheridia are embedded in cavities sunk 



in the tissues between the chambers 



and lined by a layer of cells whose 



walls are often deep purple in colour. 



Each cavity is oval in shape, has a 



tubular opening upwards, and contains 



a single large antheridium , which is 



attached by a short stalk at the base. 



The development of the antheridium 



is essentially similar to that in Pellia, 



and the antherozoids when mature 



are liberated by the bursting of the 



antheridium and are extruded out of 



the chamber in a drop of milky liquid 



(Fig. 387). They are subsequently 



transferred to the archegoniophore, 



possibly through the agency of dew or 



rain falling on the upper surface of the 



antheridiophore. Mites have been found 



in the chambers of the archegoniophore, 



Fig. 387. — Marchantia pohmorpha. Mature , . , . , , • 1 „j- „ 



antherozoid. {After Woodburn.) bearmg antherozoids on their bodies, 



