MOSSES AND LIVERWORTS. 



265 



that reaches them. There is, in the centre of the stem, 

 a thread of strong wiry cells ; and round these, forming 

 a sort of bark to the stem, is a cylindrical mass of 

 water-absorbing cells of a peculiar character. 



They are large, empty, and strengthened by woody 

 bands, which cover the inside of the cell and give it 



Fig. 33. — Pfa ■ Moss, Sphagnum, (i) Part of s em highly magnified, showing 

 cistern ceils on the o itside. (2) Leaf in transverse and (3) in longitudinal section. 

 (4) I eaf seen from above. (.^) Green cells, (t) Water-holding or cistern cells, 

 (w ) Pore by which water enters. 



sufficient rigidity to support itself when full of water. 

 Each has also a pore to admit the water. These cells 

 act, therefore, like a circle of capillary tubes placed 

 round the central part of the stem, and raise the water 

 to the leaves, which possess similar cistern-like or water- 

 holding cells. The cistern-cells are very large as com- 

 pared with the green assimilating cells placed above 

 and between them (see Fig. 33). Branches are given 



