HE PA TIC A E. MA R CHA NTIEAE. 



161 



113) the apex that is to bear the antheridia divides repeatedly before they begin to be 

 formed, and the whole collection of apices thus formed produces antheridia ; the older 



FIG. 112. /, II Fegatella cornea. I Longitudinal section through the apex of a thallus ; L the scales (lamellae) of the 

 under side of the thallus, A' the air-chambers formed on the upper side and gradually roofed over during the formation 

 of the epidermis E. II Surface-view of a portion of the thallus seen from above. ///, IV.. , VMarchantia polymorpha ; 

 development of the stomata on a receptacle in longitudinal section ; Sp the cells from which the barrel-shaped stomata are 

 formed, and which at first lie close to one another; the canal leading to the air-chamber is subsequently formed between 

 them. In V the cells containing chlorophyll are beginning to shoot out from the floor of the air-chamber. // after 

 Leitgeb, the other figures from nature. 



FIG. 113. Marchantia polymorpha. A a horizontal branch t with two ascending male receptacles hit. B vertical 

 longitudinal section through a male receptacle hu which is still developing and the part of the flat shoot from which it 

 springs ; bb scales, h rhizoids in a ventral channel of the receptacle ; oo the openings of the cavities in which the 

 antheridia a are placed. C a nearly ripe antheridium ; st its stalk, w the wall. D two spermatozoids magn. 800 times. 



ones are in the centre of the disk, and groups of them succeed one another from the 

 centre to the circumference where the apices of the shoot are placed, each outer group 



