Thesis (Ph. D.)--University of Illinois, 1920. / Vita. "Reprinted from Transactions of the Illinois State Academy of Science, vol. 14, 1921." "The common garden bean ... was chosen for these experiments." p. 4. Bibliography: p. 24.

Thesis (Ph. D.)--Cornell University, 1926. / Reprinted from New York. Agricultural experiment station. Memoir 106, May 1927. "Literature cited": p. 59-63.

Akademisk avhandling--Uppsala. / Summary in English. Bibliography: p. 103-108.

Thesis--University of Wisconsin. / Bibliography: leaves 73-77.

Thesis (M.S.)--Rutgers University, 2008. / "Graduate Program in Plant Biology." Includes bibliographical references (p. 42-46).

Thesis (doctoral)--Universität Bern, 1901. / Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1966. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin, 1966. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliography.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1959. / Typescript. Abstracted in Dissertation abstracts, v. 19 (1959) no. 12, p. 3105. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 152-159).

The objectives of this thesis were to trace the developmental pathways of somatic embryos of an abscisic-acid independent line of Larix x eurolepis. to catalogue the phenotypes of mature embryos, to determine critical stages of development and to attempt to increase the number of maturing somatic embryos. The low rate of maturation could not be entirely explained by differences in phenotypes of early embryos, critical stages of development, or the lack of plant growth regulators in the medium. In addition, the shape and epidermal type of the mature embryo did not always determine the type of epicotyl produced, nor did it affect the rooting and mortality rates. Six types of embryonal structures were evident in the aggregates of line 2086: (1) a smooth (SEMLS) or (2) rough (REMLS) embryonal mass subtended by a cylindrical, compact, long suspensor. (3) a rough embryonal mass subtended by a long, loose suspensor (REMLLS). (4) a rough embryonal mass subtended by a suspensor arising from greater than one quarter of the surface area of the embryonal mass (REMST). (5) a rough embryonal mass subtended by a short, compact, cylindrical suspensor (REMSS). and (6) a cluster of meristematic cells which may or may not have single suspensor cells attached (MC). For isolated embryonal structures of all types, to continue development into a nodule or a mature embryo was the least common fate, while proliferation and developmental arrest were more common. In general, the more organized embryonal structure types (SEMLS and REMLS) had higher rates of maturation compared to the other 4 types but the most common fate was still developmental arrest (74% SEMLS. 62% REMLS), followed by proliferation (10% SEMLS. 30% REMLS), and nodule or embryo development (16% SEMLS. 9% REMLS). REMLLS and REMST embryonal structures became developmentally arrested or proliferated (43-47%) while the rate of nodules/mature embryos production was 9-11%. Neither individual REMSS nor MC structures produced any nodules or mature embryos, but REMSS had a lower rate of developmental arrest (81%) and a higher rate of proliferation (19%) than MC (89% and 11% respectively). Embryos at more advanced stages of development were less likely to die, become developmentally arrested or become nodules, but more likely to become mature embryos than embryos at less advanced stages of development. A critical stage of development appeared to be the focal zone stage at the formation of a complete polyphenol band around the basal end of the embryonal mass. At this stage, the majority of immature embryos became mature embryos (61%) while only 3% of the embryos died. 10% became developmentally arrested, and 20% became nodules. The majority of mature somatic embryos were normally proportioned with a smooth epidermis (43%) rather than vitrified (12%). normal with a rough epidermis (12%) or misshapen (smooth or rough. 33%). The shape of the mature embryo was associated with the type of epidermis, with mature somatic embryos with normal proportions more likely to have smooth epidermis (78%) than a rough epidermis (22%) while mature embryos with abnormal proportions were as likely to have a smooth epidermis as a rough epidermis. The shape of the mature embryo was associated with the shape of the epicotyl produced. Normal-smooth, mature embryos were more likely to produce normal-smooth epicotyls (73%) than twin epicotyls (21%), vitrified epicotyls (2%) or misshapen epicotyls (5%) compared to vitrified mature embryos (42% normal-smooth epicotyls, 34% twin epicotyls, 23% vitrified epicotyls, 1% misshapen epicotyls) or misshapen mature embryos (22% normal-smooth epicotyls, 47% twin epicotyls, 7% vitrified epicotyls, 24% misshapen smooth/rough embryos). The number of mature embryos which germinated or died was not associated with either the epidermal quality or the shape of the mature embryo. Few SEMLS or REMLS embryonal structures responded to auxin and cytokinin treatments. There appeared to be a trend towards less developmental arrest and proliferation and more nodules/mature embryos produced on media with no auxin compared to media with 2,4-D and a trend towards more developmental arrest and fewer nodules/mature embryos on media without BA compared to media with BA. Only nodules on media without plant growth regulators produced roots or cotyledons. There was no effect of embryonal structure type (SEMLS or REMLS), or sucrose concentration (58 μM or 174 μM) on the maturation of immature embryos, but on media without ABA, fewer immature embryos proliferated or became developmently arrested and more embryos became nodules or mature embryos than on medium with 6-24 μM ABA. / Graduate