EFFECT OF GROWTH REGULATORS AND HERBICIDES ON NORMAL AND WOUND PERIDERM ONTOGENY IN FRAXINUS PENNSYLVANICA SEEDLINGS*

Summary. IAA, GA, kinetin, 2,4-D and naptalam were applied at 100 or 1000 ppm in lanolin to wounds made at the top of the hypocotyl of Fraxinus pennsylvanica Marsh. seedlings. Formation of normal periderm was prevented in the hypocotyl below the wounded tissue by 1000 ppm IAA or naptalam and 100 or 1000 ppm 2,4-D. IAA or naptalam at 100 ppm and GA or kinetin at 100 or 1000 ppm retarded normal periderm development. Wound periderm development was prevented only by 1000 ppm 2,4-D. Wound-stimulated development of normal periderm in tissues near the wound was prevented by 1000 ppm kinetin and 100 or 1000 ppm 2,4-D. Anomalous growths which appeared morphologically similar to nascent roots developed in the wounded hypocotyl section of seedlings treated with 1000 ppm naptalam and 100 or 1000 ppm 2,4-D. Identical growths were found in unwounded portions of the hypocotyl of seedlings treated with 100 or 1000 ppm 2,4-D. The data emphasize differences in physiological control of normal and wound periderm development. Effets de substances de croissance et d'herbicides sur l'onlogénie du pérderme normal ou blessé dans des plantules de Fraxinus pennsylvanica.     

Regional Indexes of Leading Indicators: An Evaluation Of Forecasting Performance

ABSTRACT Indexes of leading indicators are used to forecast short-run changes in economic activity in many states and metropolitan areas. This article examines the forecasting performance of a sample of such regional indexes over several business cycles. Although these indexes vary across regions, the results show that they do provide forecasts of recessions and recoveries and also exhibit some potential for forecasting quantitative changes in regional employment.     

Movement of Injected Dyes in Gymnosperm Stems in Relation to Tracheid Alignment

The path of upward movement of acid fuchsin dye was traced inpole-size stems of Japanese larch (Larix leptolepis Murr.),European larch (Larix decidua Mill.), Lawson cypress (Chamaecyparislawsoniana (A. Murr. Parl.)), Sitka spruce (Picea sitchensis(Bong. Carr.)), Norway spruce (Picea abies (L.) Karst.), andScots pine (Pinus sylvestris L.). In all of these species amarked, preponderantly clockwise spiral pattern of dye ascentwas observed. In general the upward movement of the dye followedtracheid alignment, except at the sapwood-heartwood boundary.The characteristic patterns of dye movement indicated that spiralgrain was much commoner than was straight grain among the pole-sizegymnosperms investigated. Large differences in spiral grainwere found among species, among trees within species, in differentannual rings within trees, and at different stem heights. Patternsof dye uptake were influenced somewhat by the method of injection.Dye injections through tubes driven into the stem were foundmore suitable for determining tracheid arrangement than wereinjections through individual roots immersed in dye. Factorsinfluencing spiral grain development and applications of thedye injection technique to spiral grain determination are discussed.     

SOME HISTOLOGTCAL EFFECTS OF DIRECT CONTACT OF PINUS RESINOSA SEEDS AND YOUNG SEEDLINGS WITH 2,4,5-T*

Summary. Direct contact of seeds and recently emerged seedlings with 2,4,5-T at 25 or 100 ppm caused abnormal development of Pinus resinosa Ait. seedlings. The first observed effect of 2,4,5-T treatment at 25 ppm was cessation of cell division and expansion in the roots. Subsequently the herbicide stimulated proliferation and expansion of parenchyma ceils in the stem and cotyledons, causing abnormal thickening of the seedlings. Parenchyma cells in the upper stem became disorganized and many of them collapsed. Callus tissue then formed in the region of tissue disintegration. The herbicide also inhibited formation of primary needle primordia and expansion of primary needles. In treated plants the cotyledons were fused to primary needles. Cell proliferation and formation of callus tissue were greater with 2,4,5-T at 100 ppm than at 25 ppm. Quelques effets histologiques du contact direct des semences et desjeunes plantules de Pintis resinosa avec le 2,4,5-T