366 



LIVERWORTS I STRUCTURE OF MARCHANTIA. 



riates in the neighbourhood of springs or waterfalls, where its 

 lobed fronds are found covering extensive surfaces of moist 

 rock or soil, adhering by the radical (root) filaments which 

 arise from their lower surface. At the period of fructification 

 these fronds send up stalks, which carry at their summits either 

 round shield-like disks, or radiating bodies that bear some 

 resemblance to a wheel without its tire (Fig. 176) : the former 

 carry the male organs, or Antheridia ; while the latter in the first 

 instance bear the female organs, or Archegonia, which afterwards 



give place to the 



Fig. 177. 



*£2 



Marchantia polymorpha.—A, portion of frond 

 seen from above ; a, a, lozenge-shaped divisions ; 

 6, b, stomata seen in the centre of the lozenges ; 

 c, c, greenish bands separating the lozenges :— b, 

 vertical section of the frond, showing a, a, the 

 dense layer of cellular tissue forming the floor of „ p „ t : nn ;<, -m^Ap. 

 the cavity d, d ; the cuticular layer, 6, b, forming s 

 its roof ; c, c, its walls ; /, /, loose cells m its 

 interior; g, stoma divided perpendicularly; h, 

 rings of cells forming its wall; i, cells forming 

 the obturator ring. 



Sporangia or Spore- 

 cases.* But besides 

 these, the frond 

 usually bears upon its 

 surface (as shown in 

 Fig. 176) a number 

 of little open basket- 

 shaped ' concepta- 

 cles, ' whose nature 

 and purpose will be 

 presently explained. 

 The green surface 

 of the frond of this 

 Liverwort is seen un- 

 der a low magnifying 

 power to be divided 

 into minute diamond 

 shaped spaces (Fig. 

 177, a, a, a) bounded 

 by raised bands (c,c) ; 

 every one of these 

 spaces has in its 

 centre a curious 

 brownish - coloured 

 body (b, b), with an 

 opening in its middle, 

 which allows a few 

 small green cells to 

 be seen through it. 

 When a thin vertical 

 of 

 the frond (b), it is 

 seen that each of the 

 lozenge -shaped divi- 

 sions of its surface 



* In some species, the same shields bear both sets of organs ; and in 

 Marchantia androgyna we find the upper surface of one half of the 

 pelta developing Antheridia, whilst the under surface of the other half 

 bears Archegonia. 



