THE HEPATIC^ OR LIVERWORTS 



167 



If we examine a cross-section of the thallus under a com- 

 pound microscope we will find the epidermis covering a large 

 chamber beneath each stomata. Within the chamber are great 

 numbers of delicate chlorophyll bearing parenchyma cells while 

 the lower cells contain little or no chlorophyll. 



The sexual organs are borne on separate plants. The female 



9' 



f 



Fia. 108. Diagrammatic representation of the life cycle of Marchantia polymorpha; a', 

 mature male plant; a", mature female plant; b' antheridium; b" archegonium; c', sperm; 

 c", ovum; d, oospore; e, young sporoplyte; f, and f", spores; g', and g", young plants. 



plants (Fig. 107, a) bear erect stalks supporting radiating struc- 

 tures which resemble the handle and ribs of an umbrella in their 

 arrangement. On the under surface of the radiating parts will 

 be found the minute flask-shaped archegonia. The male plants 

 (Fig. 107, b) bear erect stalks supporting disk-shaped bodies, 

 on the upper surface of which will be found minute openings 

 into cavities containing the antheridia. The fertilization is 

 the same as in the ferns and mosses. The stalk of the female 



