MARCHANTIA. 



[ 489 ] 



MARCHANTIA. 



several layers of cells, which contain much 

 chlorophyll. The inferior epidermis is 

 clothed with radical hairs, which exhibit a 

 remarkable spiral marking-, arising from the 



E rejection of a spirally deposited secondary 

 iver in the interior of the tube. 

 The fronds do not readily develop spo- 

 ranges in shady places; but when exposed to 

 the light, they are produced at the ends of 

 the ribs, at the base of the terminal notches 



Fig. 445. 



Marchantia polymorpha. 



Plant with antheridial receptacles (male). 



Nat. size. 



of the lobes. The male structures are pro- 

 duced on different plants from the female ; 

 but both are borne on peculiar stalked re- 

 ceptacles. The first appearance of one of 

 these receptacles is as a little green papilla 

 surrounded by reddish scales, at the end of 

 one of the principal ribs. As it enlarges, it 

 pushes its way through the scales ; and the 

 rib on which it is borne elongates to form 

 a pedicel, on which it is raised up perpen- 

 dicularly above the surface of the frond, 



Fig. 446. 



Marchantia polymorpha. 



Plant with fertile receptacles (female). 



Nat. size. 



ultimately acquiring the form of an ex- 

 panded cap. In the male receptacles it has 

 a sinuate margin (fig. 445) ; and in the female 

 the border is developed into eight or nine 

 thick cylindrical lobes (fig. 446). 



The male receptacle is concave above, 

 with papillae consisting of the mouths of 

 flask- shaped cavities, in each of which is 

 formed an antheridium (fig. 447). These 



Pig. 447. 



Marehantia polymorpha. 



Section through an antheridial receptacle, showing 



flask-shaped cavities containing the antheridia. 



Magnified 25 diameters. 



antheridia are oval cellular bodies lodged in 

 the expansion of the cavity, with a lono* 

 neck projecting upward through the mouth 

 of the flask-shaped excavation. The cells 

 of the interior of the lower part of the an- 

 theridia produce spermatozoids (PI. 40. fig. 

 SSJ). The lower surface of the receptacle is 

 clothed with membranous processes and 

 hairs. 



The female receptacles are somewhat 



Fig. 448. 



Marchantia polymorpha. 



A sporangial receptacle seen from below. 



Magnified 5 diameters. 



