. Plant life, considered with special references to form and function. Plant physiology. 230 PLANT LIFE. irregularly thickened (see fig. 401). The strains caused by the unequal absorption and loss of water burst the sporangium at some definite j)oint. This line of dehiscence is often between a pair of large sad- dle-shaped cells (fig. 401). 324. Sporophylls. — In many of the ferns the leaves which produce sporangia are not different from the foliage. Fig, 232. Fig. 233. Fig 232.—Diagram nf a longitudinal and transverse section of the very young capsule of a true mobS ilh yma). The transverse s
. Plant life, considered with special references to form and function. Plant physiology. 230 PLANT LIFE. irregularly thickened (see fig. 401). The strains caused by the unequal absorption and loss of water burst the sporangium at some definite j)oint. This line of dehiscence is often between a pair of large sad- dle-shaped cells (fig. 401). 324. Sporophylls. — In many of the ferns the leaves which produce sporangia are not different from the foliage. Fig, 232. Fig. 233. Fig 232.—Diagram nf a longitudinal and transverse section of the very young capsule of a true mobS ilh yma). The transverse section is taken along the line AJ<. <^ the mother cells of the spores ; f, the columella ; h. intercellular space. The constriction at the top marks the limit of the lid. The part below the sporangium is the neck, with nutriti\'e tissues,—( )riginal. Fig, 233,—A leaflet of a fern [As/'iditn") seen from the back, Ei,ght sori arc shcAvn, each covered by its own indusiurn, /, Magnihed 2 diam,—^^fter .Sachs, leaves. In others, certain leaxes are so siiccialized for bearing the sporangia that they lose their nutriti\e function in part or entirely. To such specialized leaves the name spuruphvll is applied. 325. Horsetails. — In the horsetails the sporangia lia\e the form of sacs, varying in number from six to twehe. They arise upon the lower face of a shiel(l-sha]ied sporojihyll (figs. 235, 236). These sporophylls are aggregated in a close cluster at the upper end of the axis, constituting \'\-hat. 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 Barnes, Charles Reid, 1858-1910. New York, H. Holt & company
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