. Physiological botany; I. Outlines of the histology of phænogamous plants. II. Vegetable physiology. Plant physiology; Plant anatomy. DEVELOPMENT OF POLLEN-GRAINS. 379 1000. Development of pollen-grains. This affords some of the most instructive eKainples of cell-division, and owing to the facility with which material can be procured and studied, has received much attention. (1) Sirperficiul phenomena. These, which can be easily traced without the eraplo3'ment of staining agents, are in brief as follows : At the period when the loculi of the anthers begin as minute elevations at the end of th
. Physiological botany; I. Outlines of the histology of phænogamous plants. II. Vegetable physiology. Plant physiology; Plant anatomy. DEVELOPMENT OF POLLEN-GRAINS. 379 1000. Development of pollen-grains. This affords some of the most instructive eKainples of cell-division, and owing to the facility with which material can be procured and studied, has received much attention. (1) Sirperficiul phenomena. These, which can be easily traced without the eraplo3'ment of staining agents, are in brief as follows : At the period when the loculi of the anthers begin as minute elevations at the end of the stamen, the external laj'er of cells, which is to serve as epidermis, is underlaid by. a group of small cells which give rise to the mother-cells of the pollen and to the lining of the anther itself. This group is termed the archesporium; by division of its inner layer, large mother-cells are produced which divide to form the pollen- grains. The division of a mother-cell may give rise to two, three, or four pollen-grains, and in some cases more, according to the Fig. 166. Fritillaria Persica. Division of the mother-cells of pollen, a, early stage, in which the threads are confused; &, the segments in course of longitudinal division; c, the nuclear spindle in profile; fZ, tlie same seen from its extremity or pole; e, division of the nuclear plate; /, separation of the derivative or daughter-segments; f?, formation of the derivative tangles and the cell-plate; A, the course of the nuclear threads in the derivative nuclei; i, longitudinal extension; /c,nuclear spindle,on the right, in profile, on the left, from its extremity; I, separation of the segments, on the left seen in pro- file, on the right from the extremity ; m, formation of the cell-plates. (Strasburger.). 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 orig
Size: 1761px × 1419px
Photo credit: © Central Historic Books / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, booksubjectplantanatomy, bookyea
