Versuche zur somatischen Beeinflussung der Organbildung pflanzlicher Embryonen
Experiments on influencing cotyledon formation in embryos ofEranthis hiemalis are reported. By treating the seeds with 100–2000 ppm solutions of 2,4-dichlorophenoxyacetic acid, 2,4,5-trichlorophenoxyacetic acid, 2-methyl-4-chlorophenoxyacetic acid, α-naphthylacetic acid and even isopropyl N-phenyl carbamate one can obtain significant increases in twinning and in cotyledon anomalies (syncotyly and pleiocotyly of all degrees). Embryos can be successfully treated until approximately 2 weeks after initial opening of the follicles. X-radiations achieve the same effect, with doses of 2000–4000r corresponding to the treatments with 1000–2000 ppm 2,4-D-solutions. By using weaker concentrations and with sudden temperature changes one can likewise raise the percentage of syn-, tri- and tetracotyls, but pleiocotyls of the higher degrees (5 and more cotyledons) appear only when more intensive methods of treatment are employed. These forms which exceed the normal range of variability arise as bud-like embryo regenerates on the as yet undifferentiated original embryo.
Persistence of 2,4-D Stimulus in Cotton Plants with Reference to Its Transmission to the Seed
1. Sixty-day-old cotton plants were treated with the sodium salt of 2,4-D (2,4-dichlorophenoxyacetic acid) in acid-equivalent amounts of 0.1, 1.0, or 10.0 mg. to determine the effect of large amounts of 2,4-D on (a) translocation of the stimulus into seed embryos formed prior to application and (b) its persistence within the plant as shown by injury to embryos subsequently formed. Cotton plants at the developmental stages of seedling, floral primordia: and anthesis were also treated with 2,4-D acid-equivalent amounts of 0.01 and 0.04 mg. to determine the effect of plant age on the transmission of the 2,4-D stimulus into seeds developed subsequent to the application. 2. All seeds from bolls (1-15 days old) set prior to treatment with 0.1 mg. or 1.0 mg. produced seedlings which exhibited symptoms of 2,4-D injury. Bolls in the 10.0-mg, series failed to develop. 3. Some seedlings from seeds produced in bolls initiated 8 weeks after application in the 0.1-, 1.0-, and 10.0-mg, series exhibited ~,4-D injury. Seeds formed 24 weeks after application did not yield malformed seedlings in any series. 4. Plants treated with 0.01 or 0.04 mg. of 2,4-D at the seedling or floral primordia stage showed no significant transmission of the stimulus into the seed embryos. 5. Seed embryos formed in bolls initiated in a 5-week period subsequent to application at the anthesis stage showed significant 2,4-D injury. 6. A discussion is presented of some factors determining whether cotton seed embryos formed subsequent to application will be injured by the 2,4-D stimulus.
The politics of affect and emotion in contemporary Latin American cinema : Argentina, Brazil, Cuba, and Mexico
Between Neo-realist Sentimentality and Modernist Shock: New Latin American Cinema and Beyond Thrilling Histories: Questions of Genre and History Affecting Legacies: Contemporary Structures of Feeling Alien/Nation: Contemporary Youth in Film Emotional Investments: Global Networks and Transnational Affective Communities