LIVERWORTS 



181 



branch of the thallus. On the under side of the thallus, especially 

 along the midrib, there are numerous rhizoids which serve the pur- 

 pose of roots, absorbing nourishment from the earth and holding the 

 plant in its place. The upper surface of the thallus is divided into 

 minute rhombic areas which can be seen with the naked eve. Each 

 of these areas is perforated by a small breathing pore or stomate which 



331 



Plants <>f marchanl ia. 



332. 



leads into a cavity just beneath the epidermis. This Bpace is sur- 

 rounded by chlorophyll-bearing cells, some of which stand in rows 

 from the bottom of the cavity (Fig. 333). The delicate assimilating 

 tissue is thus brought in close communication with the outer air 

 through the pore in the thick protecting epidermis. 



At various points on the midrib are little cups which contaiu 

 small green bodies. These bodies are buds or gemma which are 

 outgrowths from the cells at the bottom <>f the cup. They become 

 loosened and are then dispersed by the rain to other places where 



they take rool and gTOW into D.6W i7 



plants. 



The mosi striking organs on the 

 thallus of marchantia are the peculiar 

 stalked bodies Bhown in Pigs. 331, 

 :;:;_'. These are termed archegonio~ 

 phores and antheridiophore8 or recepta- 

 cles. Their structure and function are 

 very interesting, bul their parts are so 

 minute thai they can be studied only 888, Section of th&lhu of marehantla 

 with the aid of a microscope magnify- Stomal* %\ a, 



ing from LOO to LOO times. Enlarged drawings will guide the pupil. 



The antheridiophores are fleshy lobed disks borne <>n shoii stalks 

 (Pig. 331), The upper surface of the disk shows openings Bcareelj 



