. Essentials of botany. Botany; Botany. 284 ESSENTIALS OF BOTANY (b) Fully formed prothallia (Fig. 205) with antheridia, arche- gonia, and rhizoids. These may best be seen with in a prothal- lium that has been held by delicate forceps and washed with a gentle stream of water from a wash-bottle. The prothallium should then be mounted, bottom side up, in a concave ground-slide and examined as an opaque object and also by transmitted light. (c) Prothallia which are developing young fern-plants (Fig. 206). In some of these study with the distribution of the chlorophyll. Tig. 206. Develop
. Essentials of botany. Botany; Botany. 284 ESSENTIALS OF BOTANY (b) Fully formed prothallia (Fig. 205) with antheridia, arche- gonia, and rhizoids. These may best be seen with in a prothal- lium that has been held by delicate forceps and washed with a gentle stream of water from a wash-bottle. The prothallium should then be mounted, bottom side up, in a concave ground-slide and examined as an opaque object and also by transmitted light. (c) Prothallia which are developing young fern-plants (Fig. 206). In some of these study with the distribution of the chlorophyll. Tig. 206. Development of the Sporophyte of a Fern. Vertical section through prothallium. an, antherozoids; ar, archegonia; c, thickened cushion, in which the foot of the young fern-plant is imhedded; rh, rhizoids; I, first leaf; r, root. (Magnified.) bodies in cells of the prothaUus. Draw. Study with the struc- ture and veining of the young fern leaf. Draw. Procure some dwarf prothallia that have been growing much crowded together and then kept for a day or two with very little water. Mount in water, examine with , and look for: (d) Antheridia best seen on the margin of the prothallium. Draw. (e) Sperms, swimming about in the water. Stain these with iodine and draw, showing the body of the sperm and its tuft of cilia. In prepared slides, if any are attainable, study the structure of an archegonium, noting: (/) The enlarged ventral portion. (9) The elongated neck. Neck canal cells and ventral canal cell. (h) The egg within the ventral portion.^ Draw. 1 See Bergen and Davis' Principles of Botany, pp. 316, Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Bergen, Joseph Y. (Joseph Young), 1851-1917. Boston, Ginn
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