. Botany all the year round; a practical text-book for schools. Botany. 264 SEEDLESS PLANTS two moistened bits of glass and hold it up to the light, keep- ing the upper surface toward you ; what is its appearance ? Observe a tiny dot near the center of the rhomboidal areas into which the epidermis is divided and compare it with your drawings of stomata (Sec. 16). What should you judge that these dots are ? 372. Rhizoids. — Wash the dirt from the under side of a thallus and examine with a lens; how does it differ from the upper ' Observe the numerous rootlike hairs, or rhizoids. What i
. Botany all the year round; a practical text-book for schools. Botany. 264 SEEDLESS PLANTS two moistened bits of glass and hold it up to the light, keep- ing the upper surface toward you ; what is its appearance ? Observe a tiny dot near the center of the rhomboidal areas into which the epidermis is divided and compare it with your drawings of stomata (Sec. 16). What should you judge that these dots are ? 372. Rhizoids. — Wash the dirt from the under side of a thallus and examine with a lens; how does it differ from the upper ' Observe the numerous rootlike hairs, or rhizoids. What is their color .' Where do they spring from ? These are not true roots, but hairs that have taken upon themselves the function of absorption, and do not imply any actual differentiation of tissues. Plant a growing thallus branch in moist earth so that the upper side will lie next the soil and watch for a week or two, noting what changes take place. What would you infer from this as to the cause of the difference between the two surfaces ? Would rhizoids be of any use on the upper side.' Stomata on the under side ? 373. Gemmae. — Look along the upper surface of some of your specimens for little saucer- shaped (in Lunularia, crescent- shaped) cupules or cavities. Notice the border, whether it is toothed or entire, and see if you can tell what the cupules contain. These little bodies, called gemmce, are a kind of bud, by which the plant propagates itself somewhat as the onion and the tiger lily do by means of bulblets. Sow some of the gem- mae on moist sand, cover them with a tumbler to prevent evaporation, and watch them develop the thalloid 504-507. — Lunularia, a common liverwort: 504, portion of a thallus of about natural size: g,g, gemmse; 505, a fertile plant with fruiting receptacles; 506, an enlarged sec- tion of one of the fruiting recepta- cles ; 507, portion of a sterile thallus slightly enlarged, showing one of the crescent-shaped gemmse from which the
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