PLANT LIFE. 



that of some of the green algse. The body is a thallus with 

 rhizoids (fig. 57). The rhizoids are usually linear aggregates 



FIG. 57. A, plants of Riccia sorocarpa, on the ground. Gametophyte phase. Nat- 

 ural size. .#, a vertical section of one of the thick lobes of the thallus, showing 

 nearly uniform structure. The thallus has nearly covered over two young sporo- 

 phytes which appear as though in the interior. Rhizoids arise from the ventral side 

 and flanks. Magnified about 25 diam. After Bischoff. 



of cells having thin walls and little protoplasm, arising from 

 the under side and flanks of the thallus. They serve to 



\a 



FIG 58. Portion of a vertical section of the thallus of Lunularia cruciata. a, 

 dorsal, 6, ventral epidermis; c, an air-pore; e, air-chamber, from whose floor rise 

 cell-filaments, d ; /, partition between adjoining air-chambers; g, colorless cells 

 containing starch, some showing net-like thickenings of the walls, others with oil- 

 bodies, k; /, a ventral scale ; /, a rhizoid. Magnified no diam. After Nestler. 



fasten the thallus to the substratum, an adaptation to the 

 terrestrial mode of life. The thallus is usually flat and 



