50 



PLANT LIFE. 



that of some of the green alg?e. The body is a thallus with 

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



Fig. 57.— -I plants I f A;ti; I icrot-,?;-/,!, on the ground. Gametophyte phase. Nat- 

 ural size A, a \ertiLal seetiun of one of the thick lobes of the thallus, showing 

 nearly uniform itrueture The thallus has nearly covered over two younj; sporo- 

 phytes which appear is thouifh in the interior. Rhizoids arise from the ventral side 

 and flanks. Magnified ahout 25 diam.— After ISischuff. 



of cells having thin walls and little protoplasm, arising from 

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



Fig 58. — Portion of a vertical section of the thallus of Lunularia criiciaia. a, 

 dorsal, /', ventral epidermis; t:. an air-pore; e, air-chamber, from whose floor rise 

 cell-filaments, d ; y, partition between adjoining air-chambers ; i', colorless cells 

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

 bodies, // ; /, a ventral scale ; /, a rhizoid. Magnihed no diam. — After Nestler. 



fasten tlie thallus to the substratum, — an adaplalion to the 

 terrestrial mode of life. The thalkis is usually flat and 



