194 



STUDIES IN CRYPTOGAMS 



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

 midrib, there are numerous rhizoids which serve the purpose 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 eye. Each of these areas is 

 perforated by a small breathing pore or stomate which leads into a 



358. 



Plants of marchantia 



cavity just beneath the epidermis. This space is surrounded by chloro- 

 phyll-bearing cells, some of which stand in rows from the bottom of 

 the cavity. (Fig. 360.) 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 contain small 

 green bodies. These bodies are buds or gemmae which are outgrowths 

 from the cells at the bottom of the cup. They become loosened and 

 are then dispersed by the rain to other places where they take root and 

 grow into new plants. 



The most striking organs on the 

 thallus of marchantia are the pecu- 

 liar stalked bodies shown in Figs. 358, 

 359. These are termed archegonio- 

 phore and antheridiophores or re- 

 ceptacles, each produced on separate 

 plants. Their structure and' function 

 are very interesting, but their parts 

 are so minute that they can be 

 studied only with the aid of a micro- 

 scope magnifying from 100 to 400 times. Enlarged drawings will 

 guide the pupil. 



The antheridiophores are fleshy lobed disks borne on short stalks. 



360. Section of thallus of marchantia. 

 Stomate at a. 



