Figures 1-12.
The initiation of organization from single cells, early embryos, and
meristemoids.
FIG. 1. Freshly isolated globular-stage embryo of Capsella bursa-pastoris Medic,
approximately 50 μ in diameter, of about 16 cells. X 535.
FIG. 2. Isolated embryo of Capsella after 10 days in culture medium containing
indoleacetic acid, kinetin, and adenine sulfate. Spherical multicellular mass was
about 425 μ in diameter, χ 65. (From Raghavan and Torrey, 1963.)
FIG. 3. Cell colonies derived from filtered cell suspensions of Convolvulus
arvensis
L. root callus plated on synthetic nutrient medium. Spherical multicellular clumps
resemble globular stage of embryo development. X 82. (From Earle and Torrey,
1965b.)
FIG. 4. Single cell of pea root callus isolated in hanging-drop culture. X 320.
(From Torrey, 1957.)
FIG. 5. Single isolated cell of pea root callus divided into 6 cells after 10 days in
hanging-drop culture on complex yeast-extract medium, χ 320. (From Torrey,
1957.)
FIG. 6. Cell colony derived from single isolated cell of pea root callus cultured
24 days on complex media in hanging-drop culture. X 250. (From Torrey, 1957.)
FIG. 7. Transection of cortical tissues of distal portion of a root segment of
Convolvulus arvensis L. cultured on synthetic nutrient medium containing 0.1 ppm
kinetin. A cortical cell with heavy cell wall has divided into many cells to form a
meristemoid which later can give rise to an adventive bud. X 525. (Torrey, unpublished results, 1958.)
FIG. 8. Section of stem pith callus tissue of Nicotiana tabacum L. grown on
synthetic medium containing indoleacetic acid and kinetin for 12 days; this section
shows the center of meristematic tissue. X 140. (From Murashige, 1964.)
FIG. 9. Section of callus tissue of Syringa vulgaris L. showing small nest of vascular tissue containing one xylem element. X 585. (From Wetmore and Rier, 1963.)
FIG. 10. Section of tobacco callus tissue grown for 16 days under same conditions
detailed in legend of Fig. 8; this section shows a nest of mature vascular elements
with reticulately thickened walls. X 140. (From Murashige, 1964.)
FIGS. 11 and 12. Squash preparations of cell colonies derived from cell suspensions
of Convolvulus root callus, photographed under polarized light. Fig. 11 shows nests
of mature xylem elements. Fig. 12 shows nests of cells in which starch grains have
been stored. Surrounding cells show no birefringence. Both, X 82. (From Earle and
Torrey, 1965b.)
71
The initiation of organization from single cells, early embryos, and
meristemoids.
FIG. 1. Freshly isolated globular-stage embryo of Capsella bursa-pastoris Medic,
approximately 50 μ in diameter, of about 16 cells. X 535.
FIG. 2. Isolated embryo of Capsella after 10 days in culture medium containing
indoleacetic acid, kinetin, and adenine sulfate. Spherical multicellular mass was
about 425 μ in diameter, χ 65. (From Raghavan and Torrey, 1963.)
FIG. 3. Cell colonies derived from filtered cell suspensions of Convolvulus
arvensis
L. root callus plated on synthetic nutrient medium. Spherical multicellular clumps
resemble globular stage of embryo development. X 82. (From Earle and Torrey,
1965b.)
FIG. 4. Single cell of pea root callus isolated in hanging-drop culture. X 320.
(From Torrey, 1957.)
FIG. 5. Single isolated cell of pea root callus divided into 6 cells after 10 days in
hanging-drop culture on complex yeast-extract medium, χ 320. (From Torrey,
1957.)
FIG. 6. Cell colony derived from single isolated cell of pea root callus cultured
24 days on complex media in hanging-drop culture. X 250. (From Torrey, 1957.)
FIG. 7. Transection of cortical tissues of distal portion of a root segment of
Convolvulus arvensis L. cultured on synthetic nutrient medium containing 0.1 ppm
kinetin. A cortical cell with heavy cell wall has divided into many cells to form a
meristemoid which later can give rise to an adventive bud. X 525. (Torrey, unpublished results, 1958.)
FIG. 8. Section of stem pith callus tissue of Nicotiana tabacum L. grown on
synthetic medium containing indoleacetic acid and kinetin for 12 days; this section
shows the center of meristematic tissue. X 140. (From Murashige, 1964.)
FIG. 9. Section of callus tissue of Syringa vulgaris L. showing small nest of vascular tissue containing one xylem element. X 585. (From Wetmore and Rier, 1963.)
FIG. 10. Section of tobacco callus tissue grown for 16 days under same conditions
detailed in legend of Fig. 8; this section shows a nest of mature vascular elements
with reticulately thickened walls. X 140. (From Murashige, 1964.)
FIGS. 11 and 12. Squash preparations of cell colonies derived from cell suspensions
of Convolvulus root callus, photographed under polarized light. Fig. 11 shows nests
of mature xylem elements. Fig. 12 shows nests of cells in which starch grains have
been stored. Surrounding cells show no birefringence. Both, X 82. (From Earle and
Torrey, 1965b.)
71