. Elements of biology; a practical text-book correlating botany, zoology, and human physiology. Biology. Rock fern, polypody. Notice the underground stem giving off roots {R) from its under surface, and leaves (C) from the upper surface. .The com- pound leaf or frond may bear sori (5) on the under side of the Section of sorus; s, sporangia; i, indusium, or covering; b, blade of the leaf. — Wossidlo. If fresh material is obtainable, it will be possible to see how the spores get out of the sporangium. A drop of glycerine run under the cover slip of a slide holding a fresh unopened spo
. Elements of biology; a practical text-book correlating botany, zoology, and human physiology. Biology. Rock fern, polypody. Notice the underground stem giving off roots {R) from its under surface, and leaves (C) from the upper surface. .The com- pound leaf or frond may bear sori (5) on the under side of the Section of sorus; s, sporangia; i, indusium, or covering; b, blade of the leaf. — Wossidlo. If fresh material is obtainable, it will be possible to see how the spores get out of the sporangium. A drop of glycerine run under the cover slip of a slide holding a fresh unopened sporangium soon causes the sporangium to snap open. If the sporangium is dry and on the under surface of the fern leaf, the spores be scattered for a considerable distance. An explanation for this snapping open of the sporangium is found when we notice that the outer walls of the cells forming the annulus are thinner than the inner walls. This allows water to escape more rapidly on one side, and pressure from without causes the cells to bend outward a sporangium. 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 Hunter, George William, 1873-1948. New York, American book company
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