. Lessons in botany. Botany. FERNS. f§9 structure of this spore-case quite carefully, since it will help us to understand better than we otherwise could the remarkable operations which it performs in scattering the spores. 263. Structure of a sporangium.—If we examine one of the sporangia in side vkw as shown in fig. 137, we note a promi- nent row of cells which extend around the margin of the dorsal edge from near the attachment of the stalk to the upper front angle. The cells are prominent because of the thick inner walls, and the thick radial walls which are perpendicular to the inner walls
. Lessons in botany. Botany. FERNS. f§9 structure of this spore-case quite carefully, since it will help us to understand better than we otherwise could the remarkable operations which it performs in scattering the spores. 263. Structure of a sporangium.—If we examine one of the sporangia in side vkw as shown in fig. 137, we note a promi- nent row of cells which extend around the margin of the dorsal edge from near the attachment of the stalk to the upper front angle. The cells are prominent because of the thick inner walls, and the thick radial walls which are perpendicular to the inner walls. The walls on the back of this row and on its sides are very thin and membranous. We should make this one. Fig- '33- Rhizome of sensitive fern (Onoclea sensibilis\ carefully, for the structure of these cells is especially adapted to a special function which they perform. This row of cells is termed the annulus, which means a little ring. While this is not a complete ring, in some other ferns the ring is nearly com- plete. 264. The lip cells.—In the front of the sporangium is another peculiar group of cells. Two of the longer ones resemble the lips of some creature, and since the sporangium opens between them they are sometimes termed the lip cells. These lip cells. 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 Atkinson, George Francis, 1854-1918. New York, H. Holt and company
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