CRYPTOGAMS 



199 



become separate individuals. The plant is attached to the 

 ground by absorptive hairs, or rhizoids. Above, the sur- 



v,r 



334. Marchantia : A, thallus with rhizoids (r), cupules (c), and archegonial 

 branch (6) ; B, section of archegonium, the fertilized egg (e) having 

 divided once; C, disk of fruiting branch cut to show sporogonia 

 (m, w, o) ; D, opened sporogonium with enveloping sheath {pe), and 

 remains of old archegonium {ar). 



face is seen on close inspection to be divided into small, 

 slightly raised areas, each with a pore at the summit. 

 The pore leads into a chamber (Fig. 335), from the floor of 

 which rise short fila- 

 ments or rows of richly ^ ^ 

 chlorophy lions cells — 

 the chief assimilatory 

 tissue. This arrange- 

 ment has the same ef- 

 fect as that of the loose 

 tissues in the leaf of 

 Flowering Plants (see 

 Fig. 382), where pores (stomates} give free passage to gases, 

 while the epidermal covering retains moisture. 



335. Section in upper part of thallus to 

 show pore (p) and assimilating cells 

 (oc). 



