. Plants; a text-book of botany. Botany. SPERilATOPHYTES : ANGIOSPEKMS 199. Fig. 168. Cross - section of anther of a lily {Butomus), showing the separating walls between the members of each pair of sporangia broken down at z, forming a con- tinuous cavity (pollen sac) which opens by a longitudi- nal slit,—After Sachs. The opening of the pollen-sac to discharge its pollen- grains (microspores) is called dehiscence, which means " a splitting open," and the methods of dehiscence are various (Fig. 167«). By far the most common method is for the wall of each sac to split lengthwise (Fig.
. Plants; a text-book of botany. Botany. SPERilATOPHYTES : ANGIOSPEKMS 199. Fig. 168. Cross - section of anther of a lily {Butomus), showing the separating walls between the members of each pair of sporangia broken down at z, forming a con- tinuous cavity (pollen sac) which opens by a longitudi- nal slit,—After Sachs. The opening of the pollen-sac to discharge its pollen- grains (microspores) is called dehiscence, which means " a splitting open," and the methods of dehiscence are various (Fig. 167«). By far the most common method is for the wall of each sac to split lengthwise (Fig. 168), which is called longitudinal dehiscence; an- other is for each sac to open by a terminal pore (Fig. 167«), in which case it may be prolonged aboye into a tube. 111. Megasporophylls. — These are the so-called " carpels " of Seed- plants, and in Angiosperms they are organized in various ways, but always so as to inclose the mega- sporangia (ovules). In the simplest cases each carpel is independent (Fig. 169, A), and is dif- ferentiated into three regions : (1) a hollow bulbous base, which contains the ovules and is the real seed case, known as the ovary; (3) sur- mounting this is a slender more or less elongated process, the style; and (3) usually at or near the apex of the style a special receptive surface for the pol- len, the stigma. In other cases several carpels to-. 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 Coulter, John Merle, 1851-1928. New York, D. Appleton and company
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