Elementary botany . Rhizome of sensitive fern (Onoclea sensibilis). of cells. Two of the longer ones resemble the lips of some crea-ture, and since the sporangium opens between them they aresometimes termed the lip cells. These lip cells are connected withthe upper end of the annulus on oneside and with the upper end of the stalkon the other side by thin-walled cells,which may be termed connective cells,since they hold each lip cell to its partof the opening sporangium. The cellson the side of the sporangium are alsothin-walled. If we now examine asporangium from the back, or dorsalUnder side
Elementary botany . Rhizome of sensitive fern (Onoclea sensibilis). of cells. Two of the longer ones resemble the lips of some crea-ture, and since the sporangium opens between them they aresometimes termed the lip cells. These lip cells are connected withthe upper end of the annulus on oneside and with the upper end of the stalkon the other side by thin-walled cells,which may be termed connective cells,since they hold each lip cell to its partof the opening sporangium. The cellson the side of the sporangium are alsothin-walled. If we now examine asporangium from the back, or dorsalUnder side of pinnaof Aspidium edge as we say, it will appear as in the spinulosum showing fruit dots . - . ~ TT (sori). left-hand figure. Here we can see how very prominent the annulus is. It projects beyond thesurface of the other cells of the sporangium. The spores arecontained inside this Fig. oil I LUST FERNS. W 535. Opening of the sporangium and dispersion of thespores.—If we take some fresh fruiting leaves of the Christmasfern, or of any one of many of the species of the true ferns justat the ripening of the spores, and place a portion of it on a pieceof white paper in a dry room, in a very short time we shall seethat the paper is being dusted with minute brown objects whichfly out from the leaf. Now if we take a portion of the sameleaf and place it under the low power of the microscope, so thatthe full rounded sporangia can be seen, in a short time we notethat the sporangium opens, the upper half curls backward as
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