. Plants; a text-book of botany. Botany. 202 PLAXT STEUCTUEES ordinary nutritive cells of the gametophyte remains, and the whole structure seems to represent a single antherid- ium. At first it consists of two cells, the large wall cell and the small free generative cell (Fig. 172, D). Later the generative cell di- vides (Fig. 172, E), either while in the pollen - grain or after entrance into the pol- len-tube, and two male cells (sperm mother- cells) are formed (Fig. 172, F), which do not organize sperms, but which function direct- ly as gametes. When pollination occurs, and the pollen has be
. Plants; a text-book of botany. Botany. 202 PLAXT STEUCTUEES ordinary nutritive cells of the gametophyte remains, and the whole structure seems to represent a single antherid- ium. At first it consists of two cells, the large wall cell and the small free generative cell (Fig. 172, D). Later the generative cell di- vides (Fig. 172, E), either while in the pollen - grain or after entrance into the pol- len-tube, and two male cells (sperm mother- cells) are formed (Fig. 172, F), which do not organize sperms, but which function direct- ly as gametes. When pollination occurs, and the pollen has been transferred from the pollen-sacs to the stigma, it is de- tained by the minute papillse of the stig- matic surface, which also excretes a sweet- ish sticky fluid. This fluid is a nutrient so- lution for the micro- spores, which begin to put out their tubes. A pollen-tube pene-. FiG. 173. Diagramofalongitudina] section through a carpel, to illustrate fertilization with all parts in place ; ^, stigma ; g, style ; o, ovary ; ai, ii, outer and inner integuments; n, base of nucel- lus ; /, funiculus ; ft, antipodal cells ; c, endo- sperm nucleus; k, egg and one synergid; p, pol- len-tube, having grown from stigma and passed trates t h r 0 U g ll the through the uaicropyle (m) to the gtigmatic SUrfaCe, LUERSSEN, en- ters among the tissues of the style, which is sometimes very long, slowly or rap- idly traverses the length of the style supplied with food by. 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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