Showing papers in "Botanical Gazette in 1942"
TL;DR: Gross development and principal tissue changes in the fruit of the apple from 1 month before full bloom throughout the growing season to fruit ripening are figured and discussed, and suggestions are made regarding the methods and the values of measurements of various parts.
Abstract: 1. Gross development and principal tissue changes in the fruit of the apple from 1 month before full bloom throughout the growing season to fruit ripening are figured and discussed, and suggestions are made regarding the methods and the values of measurements of various parts. 2. Interpretation of the apple as five drupelike carpels contained within the fleshy torus or receptacle has seemed to describe the structures observed. 3. The curve of gross development of the entire fruit is nearly a straight line for the early summer variety (Early Harvest), but for each successively later-ripening variety (McIntosh and Rome) the curve flattens as the season progresses. Although perhaps associated with environment, the rate of growth is shown to be a varietal characteristic, in which each successively later-ripening variety has a slower rate. 4. The cartilaginous portion of the carpels develops rapidly for 2-4 weeks after full bloom, reaching maximum size in transverse diameter the earliest of any of the tissues ...
85 citations
TL;DR: In this paper, a quantitative study of ethylene production in relation to the respiration of pears has been made, and the emanation of the ethylene in air at 20⚬ C, as well as at higher and lower temperatures in modified atmospheres, has been studied.
Abstract: 1. A quantitative study of ethylene production in relation to the respiration of pears has been made. The emanation of ethylene in air at 20⚬ C., as well as at higher and lower temperatures in modified atmospheres, has been studied. 2. In fruit in air at 20⚬ C. the rate of ethylene production increases during the climacteric rise in respiration, reaches a peak at the respiratory climax, then declines during the post-climacteric period. During the climacteric rise, ethylene production increases seven- to eighty-fold, while rate of respiration approximately doubles. 3. Each variety was found to have a characteristic maximum rate of production. The maximum rate for Bartlett, a variety which maintains its capacity to ripen for only a short period of time when kept at a storage temperature of 0⚬ C., is 3.25-4.48 ml. per kg.-day. The maximum rate for Anjou, a variety which maintains its capacity to ripen for a long period of time when kept at cold storage temperatures, is 0.57-0.78 ml. per kg.-day. The maximum ...
82 citations
TL;DR: In Eureka lemon the succession of the whorls of the flower parts is acropetal and the courses of the vascular bundles and the general histological features of the floral parts are described.
Abstract: 1. In Eureka lemon the succession of the whorls of the flower parts is acropetal. The nectary or gynoecial disk originates after the carpels. 2. The courses of the vascular bundles and the general histological features of the floral parts are described. 3. The gynoecium is considered a whorl of carpels around the apex of the receptacle which extends past the level of the placenta. 4. Development of the fruit involves a period of cell multiplication throughout the ovary, followed by one of cell differentiation. Differentiation in the pericarp produces three zones: (a) an outer exocarp which is compact and contains oil glands, the flavido; (b) the mesocarp which is spongy and becomes most highly developed close to the inner pericarp, the albido; (c) the inner pericarp which is compact and from which the juice sacs diverge. 5. Primordia of juice sacs appear just before opening of the flower and occur on the adaxial surface of each carpel. After the juice sacs grow across the locules, a portion of each enlarg...
45 citations
TL;DR: Water and probably mineral nutrients move across Phaseolus-Biloxi graft unions readily, but elaborated foods do not appear to cross such unions.
Abstract: 1. Biloxi plants or parts of Biloxi plants, subjected continuously to daily photoperiods of 17 or more hours, were used as one component of all grafts reported in this work. Plants of this variety do not develop sufficient flower-forming stimulus on long photoperiods to cause floral initiation. They therefore served to determine whether or not a flower-inducing stimulus was transmitted across the graft unions. They are referred to as receptors and the plant or plant parts grafted to them as the donors. 2. The donor components were from Agate, Batorawka, or Biloxi varieties of Soja max, or from Red Kidney, Plentiful, Black Valentine, or Dwarf Horticulture varieties of Phaseolus vulgaris. 3. Methods of grafting employed were approach grafting of stems, splice grafting of petioles, splice grafting of stems, and bud grafting. 4. A total of 490 Agate-Biloxi approach grafts were made and all formed strong unions. Approximately 50 per cent of the Biloxi receptors formed flower primordia. This percentage was some...
41 citations
TL;DR: The dormant spores are considered to lack sufficient available Z factors for germination, which may also be met by treatment with heat, cold, acetate, or pyridine, which are thought to change the Z factors in the spores from an unavailable to an available form.
Abstract: Spores of Phycomyces germinate poorly at 26⚬ C. on a mineral-dextrose agar medium containing thiamine. The percentage of germination increases somewhat with age of the spores, reaching a maximum of about 12 per cent after 2 1/2 months. It is affected slightly by the temperature at which the spores are grown and by their exposure to light during development. The addition to the medium of extracts of potato tubers or other natural products, of hypoxanthine and a DR fraction (Z factors), or of acetate and some other organic acids increases germination to nearly 100 per cent. Treatment of spores with aqueous pyridine, 2 hours' exposure to temperatures of 11⚬ or 15⚬, or treatment for 30 minutes to 1 hour at 50⚬, has the same favorable effect. Failure of the spores to germinate on the basal medium is interpreted as a dormancy phenomenon. The dormant spores are considered to lack sufficient available Z factors for germination. The extracts of natural products or the Z factors furnished in the medium supply the d...
38 citations
TL;DR: In general, variations in calcium and nitrate in the nutrient medium produced greater differences in growth and fruitfulness of plants over wider ranges of concentrations than were obvious with the other elements.
Abstract: 1. Four experiments were carried out to measure the influence of environmental conditions on the ascorbic-acid content of Bonny Best tomatoes. Two of them were designed to test the influence of macronutrient supply and the others measured the influence of climatic environmental factors. 2. In sand cultures, growth and fruitfulness could be correlated with minor variations in nutrient composition. 3. Gross appearances of plants grown in eighty-seven different solutions are discussed and quantitative data presented for growth and fruitfulness. These data are reduced and analyzed by statistical methods. 4. In general, variations in calcium and nitrate in the nutrient medium produced greater differences in growth and fruitfulness of plants over wider ranges of concentrations than were obvious with the other elements. Interactions of the effects of various elements were noted. 5. Ascorbic-acid content of the fruit was significantly higher in some sulphate-deficient treatments and significantly lower in potassi...
37 citations
TL;DR: The lateral entry of water into older portions of Citrus roots is measurable, and ``they probably provide the major avenue of ingress during certain seasons of the year'' and the root lenticels may be the structures through which water most readily enters older portions.
Abstract: 1. A potometric device for the quantitative determination of water movement into roots is described. The apparatus is designed so that it may be attached to any part of the root. 2. Experiments with young roots of corn indicate that the rate of water entry increases from the zone proximal to the root cap to a maximum at a point 10 cm. from the root tip. In most cases the rate decreases above this level in roots more than 10 cm. in length. 3. The lateral entry of water into older portions of Citrus roots is measurable, and ``they probably provide the major avenue of ingress during certain seasons of the year. The root lenticels may be the structures through which water most readily enters older portions of the root.
37 citations
TL;DR: The pathogenicity of strains of U. zeae seems to be correlated with their ability to produce auxin in a bacto-tryptone or a synthetic medium, and its action may be hydrolytic.
Abstract: 1. The extraction of auxin by ether and by water from smut tumors of corn and other materials, frozen and vacuum dried, was studied. For a given weight of smut tumors, water extraction yields the greater amount of auxin. Dry ether extracts are not active. Water is necessary for the liberation of auxin from the tissues. Its action may be hydrolytic. 2. Smut tumors of corn yield auxin slowly with either water or ether extraction. The auxin is almost completely removed from the fungus, Ustilago zeae, in one ether extraction. 3. Smut tumors from corn leaves or stems yield more auxin than healthy leaves or stems. 4. Strains of U. zeae grown on a synthetic medium containing neither proteins nor amino acids are able to produce auxin. 5. Extracts of both types of medium upon which U. zeae had grown for 2 months contained much auxin and practically the same amount in each case. 6. The pathogenicity of strains of U. zeae seems to be correlated with their ability to produce auxin in a bacto-tryptone or a synthetic m...
35 citations
TL;DR: It was shown that the major coils of metaphase are derived from numerous coils of small gyre size which are progressively reduced in number by uncoiling at the same time that the gyres are increasing in diameter.
Abstract: 1. The genetical and environmental control of major coiling has been studied in Tradescantia from a quantitative point of view. The number of major coils per chromosome was shown to be under complex genetical control. 2. The use of heat treatments revealed that the coiling cycle during meiotic prophase could be broken down into two stages: (1) the initiation of the coils, the spiralization phase; and (2) the loss of coils, the despiralization phase. It was thus possible to show that the major coils of metaphase are derived from numerous coils of small gyre size which are progressively reduced in number by uncoiling at the same time that the gyres are increasing in diameter. Using temperature from 3.5⚬ to 42⚬ C., it was found that at high and low temperatures the despiralization process was accentuated, leading to greater contraction of chromosome length. The greatest number of major coils was found at 27⚬ C. The effect of temperature on the number of major coils was considered both from the standpoint of ...
35 citations
TL;DR: Biochemical and thermodynamical evidence is introduced which suggests that such dissociations condition increased protoplasmic swelling pressure, respiration, and polysaccharide hydrolysis, as well as altering development.
Abstract: 1. The centrifuge method was used to determine protoplasmic viscosity in cortex cells (and in some instances in ray and pith cells) of bean petioles and stems which had been daubed with lanolin preparations of indole-3-acetic acid, indole-3n-propionic acid, and α-naphthalene acetic acid. 2. Unilateral applications of the growth substances initially conditioned negative curvatures, in which instances the protoplasmic viscosity was lower in cells on the faster growing sides of the petioles and stems than in cells on the slower growing sides, and likewise lower than in control petioles or stems. When subsequent positive curvatures resulted, the viscosity was decreased about equally on the treated and untreated sides, except in the case of petioles treated with a paste containing 100 mg. of indole-3n-propionic acid per gram of lanolin, in which instance the viscosity was lower on the untreated sides. 3. Applications of indole-3n-propionic acid or α-naphthalene acetic acid to the tops of decapitated plants res...
31 citations
TL;DR: Variations in amounts of calcium and nitrate in the nutrient medium resulted in greater differences in fruitfulness over wider ranges in concentrations than did the other elements.
Abstract: 1. A population of 1044 plants of an inbred strain of Bonny Best tomatoes was grown in sand culture. The effects of eighty-seven different nutrient solutions varying in the relative proportions of macro-nutrient elements were studied in relation to fruitfulness and the occurrence of blossom-end rot. The data were reduced and analyzed by statistical methods. 2. In general, variations in amounts of calcium and nitrate in the nutrient medium resulted in greater differences in fruitfulness over wider ranges in concentrations than did the other elements. 3. Greatest fruitfulness occurred in treatments relatively high in nitrate and low in sulphate and phosphate in the anion triangle and in treatments relatively high in calcium and low in magnesium and potassium in cation triangle. 4. The percentage of diseased fruits on each plant increased with decreasing calcium concentrations in the nutrient medium. This correlation is largely independent of magnesium and potassium concentrations, and no correlation with an...
TL;DR: The effects of sulphur deficiency on the size of black mustard plants was evident early, but chlorosis of the leaves appeared late, and the main symptoms were the short plants, the yellow-green color of the upper leaves, the small leaves and the thin stems.
Abstract: 1. The effects of sulphur deficiency on the size of black mustard plants was evident early, but chlorosis of the leaves appeared late. The main symptoms were the short plants, the yellow-green color of the upper leaves, the small leaves and the thin stems. The stems were hard and the leaves had a stiff texture. Anthocyanin development in leaves and stems, the hairy nature of these organs, and the pimply character of the young leaves were prominent. The weight of the tops was reduced more than that of the roots, causing a low top-root ratio; but of the tops the stems were affected more than the leaves. Stem elongation was not prominent. 2. The sulphur-deficient stems were low in moisture. They were very high in ammonia, amino acids, and amides. Nitrates accumulated to a certain extent. The minus-sulphur stems were very low in reducing sugars, but they were much higher in sucrose and starch and also somewhat higher in acid-hydrolyzable carbohydrates than the stems of the plus-sulphur plants. Little volatile...
TL;DR: Meiotic spindle irregularities in Mentha piperita, M. spicata, and six of their interspecific hybrids were investigated, including both timing and structural variation in spindle development and behavior.
Abstract: Meiotic spindle irregularities in Mentha piperita, M. spicata, and six of their interspecific hybrids were investigated, including both timing and structural variation in spindle development and behavior. These spindle abnormalities are dependent upon the action of a gene transmitted from M. spicata to all its offspring. The effect of the gene is to induce an unstableness of spindle form and behavior which is subject to environmental differences. The gene exerts no directive influence on the spindle change, for irregularities were of many kinds.
TL;DR: With the exception of root tips, the greatest catalase activity was measured in the organs with the earliest and most extensive histological responses, and these organs were also the ones which became chlorotic, and a possible correlation between this condition and the extreme catal enzyme activity was suggested.
Abstract: 1. Plants were grown 10 days on control and boron-deficient solutions. Samples representing the entire plant were taken every second day for anatomical examination and catalase determinations. 2. External symptoms of boron deficiency were described for the entire plant and were correlated where possible with internal symptoms. 3. Anatomical responses were evident in stem and root tips, second leaves, and stems 2 days after the boron-deficient treatment was started. In the stem tips, cell enlargement and collapse occurred in the region of cell division and in the cortex of more mature portions. The stelar cells of the root tip were similarly affected. Tissues which were actively growing at the beginning of the treatment were the most responsive. Hypocotyls were very inactive. 4. Hypertrophy of the xylem parenchyma and the parenchyma in the regions where the internal and external cambiums usually originate was the first visible response in organs with differentiated vascular bundles. 5. Boron-deficient orga...
TL;DR: In these varieties floral differentiation continued over a period of months during that part of the winter when leaf formation and growth did not take place or were at a minimum, and in the most distal secondary axes it was completed just prior to or during expansion of the bud.
Abstract: 1. Buds of Lula and Nabal avocado collected during the winters of 1940-41 and 1941-42 at Orlando, Florida, and from the same varieties at Homestead, Florida, during the winter of 1941-42, were studied. In these varieties floral differentiation continued over a period of months during that part of the winter when leaf formation and growth did not take place or were at a minimum. 2. Differentiation began with development of the proximal secondary axes in late October or November. There was a year-to-year variation in the time of this development for a given variety, and between varieties, as well as between trees of the same variety in different sections. 3. The first identifiable flowers appeared on the lowest inflorescences (secondary axes) in the January buds of both varieties in the Orlando district and of the Lula variety in the Homestead district; but in the Nabal variety at Homestead they had not yet appeared on March 10, 1942. Differentiation proceeded distally during the winter, and in the most dis...
TL;DR: The relationship of the Bellefontaine silt loam soil profile, with its inclusions, to the root development of the native species in the maple-oak forest was studied during the summers of 1938-1940.
Abstract: 1. The relationship of the Bellefontaine silt loam soil profile, with its inclusions, to the root development of the native species in the maple-oak forest at Wychwood, Lake Geneva, Wisconsin, was studied during the summers of 1938-1940. Stations were selected to obtain a cross-section of the varying conditions in the forest. 2. Sixteen station types were investigated by the trench method of root-distribution sampling. In six of the station types a new, square method of trenching afforded more accurate measurement of the heterogeneous root distribution than did the rectangular trenches most commonly employed. 3. Root systems of herbaceous and woody seedlings in the various station types were excavated and their relation to the upper horizons noted. Large specimens of sugar maple, red oak, and white oak also were partially excavated. Root volumes were obtained from surface cubic-foot samples in each station type. Cicada and earthworm activity was observed. 4. Greatest concentration of the smallest roots, 0...
TL;DR: Chromosomal association and behavior during meiosis was determined from duplicate collections of twelve plants and single collections of eight plants from open-pollinated populations of Dactylis glomerata, with significant differences between the dates of collection and among plants.
Abstract: 1. Chromosomal association and behavior during meiosis was determined from duplicate collections of twelve plants and single collections of eight plants from open-pollinated populations of Dactylis glomerata. 2. The average number of quadrivalents per sporocyte ranged from 2.42 to 4.39 for the twenty plants. The differences among plants and between dates of collection were statistically significant. 3. The percentage of metaphase I sporocytes with univalents varied from 0 to 16.8. P was less than 0.05 and 0.01, respectively, for comparisons of differences among plants and between dates of collection. 4. From 1.7 to 34.0 per cent of the anaphase I sporocytes of the different plants had lagging chromosomes which were dividing equationally. The difference between dates of collection was significant. For comparison of variance due to plants with the interaction plants x days, F was slightly less than F for P of 0.05. From 0.5 to 13.8 per cent of the anaphase I sporocytes had dicentric chromatid bridges accomp...
TL;DR: Preparations of chloroplast substance isolated by fractional centrifugation showed less protein contamination than when flocculation with calcium chloride or freezing was used.
Abstract: 1. Preparations of chloroplast substance isolated by fractional centrifugation showed less protein contamination than when flocculation with calcium chloride or freezing was used. 2. The chloroplast substance of spinach leaves has been found to contain about 54 per cent protein (N x 6.25), 34 per cent lipoid, 5 per cent chlorophyll, and 7 per cent ash. About 11 per cent of the total nitrogen is found in the lipoid fraction and less than one-third of this lipoid nitrogen is accounted for by chlorophyll.
TL;DR: It was determined by means of microchemical observations that the degree of greenness of the leaves reflected what percentage of the total capacity of starch reserves the plant possessed, and plants in this category are therefore considered deficient in carbohydrates even though the absolute amount of starch is higher than in the former case.
Abstract: 1. Methods are given for obtaining in the field quantitative records of plant weight, number and dimensions of leaves, and percentage deficiency, if any, of stored water in the leaf of the pineapple plant. 2. The potential absorptive capacity of the root system is indicated by records of root anchorage in pounds and percentage of main roots and lateral rootlets displaying white non-suberized tips. 3. Only white, semi-meristematic tissue at the leaf base is analyzed for nitrate, potassium, and phosphorus. Regardless of age in months, prior to blossom-bud development, the leaf employed for analysis is always in precisely the same easily recognized stage of development (fig. 6). 4. After emergence of the determinate blossom cluster, no more analyses for nitrate are made, for the external nitrogen supply after budding is essentially without influence upon the development of the original plant and the fruit it may produce. 5. Until the specialized storage tissue of the leaf becomes practically depleted of wate...
TL;DR: Ambrosia trifida, a short-day plant, after starting growth on long day, was subjected to two, ten, and twenty photoinductive cycles at each of three photoperiods-15, 12, and 6 hours to study sex expression and rate of maturity and yield of fruit.
Abstract: 1. Ambrosia trifida, a short-day plant, after starting growth on long day, was subjected to two, ten, and twenty photoinductive cycles at each of three photoperiods-15, 12, and 6 hours. Following this treatment, the plants were returned to a long-day bench to complete growth. 2. Rate of maturity was most rapid and yield of fruit was greatest in the plants exposed to twenty photoinductive cycles at the 12-hour photoperiod. 3. Sex expression as measured by development of pistillate flowers in the position usually occupied by staminate increased with increasing numbers of photoinductive cycles and decreasing lengths of photoperiod, being greatest in the plants exposed to twenty photoinductive cycles at the 6-hour photoperiod.
TL;DR: Deposition of lignin was found to be a function of living parenchymatous cells and occurred in the vicinity of a wound or fungus infection, and in a healthy plant these cells did not become lignified.
Abstract: Cucumber seedlings were grown in sand culture at high and low levels of nitrogen nutrition during several different seasons of the year. The seedlings were artificially inoculated at different ages with a fungus of the Pythium type, causing the damping-off disease, and the relative resistance or susceptibility to infection noted. The more important results are as follows: 1. Young seedlings were more susceptible to infection than older ones. 2. Seedlings grown under the relatively poor light conditions of winter remained susceptible to infection for a longer time than those grown under the good light conditions of late spring and early summer. 3. Seedlings grown with no external supply of nitrogen remained susceptible to infection for a longer time than seedlings supplied with a complete nutrient solution containing nitrogen. 4. Resistance to infection was accompanied by a deposition of lignin in the cell walls of the tissue surrounding the area of infection. Susceptibility to infection was accompanied by...
TL;DR: Application of phosphate to plants high in phosphorus and deficient in nitrate might well bring about still further nitrate deficiency and decrease in yields, although the suppressing action of even high concentrations of phosphate on nitrate absorption is less common than that of nitrate on phosphate intake.
Abstract: 1. In the pineapple plant a low reserve of nitrate was found adequate for greatest possible yields of fruit when carbohydrates were low. In contrast, when carbohydrates were high maximum production was not obtained unless the plants were essentially filled to capacity with nitrate. In practically the same location a difference of 75 per cent in nitrogen requirements was found in successive years (37). 2. When the concentration of carbohydrates is low and relatively little nitrate therefore supplied, phosphate is freely absorbed, even from soils rather low in phosphorus. In the same site under environmental conditions more favorable for carbohydrate accumulation more nitrate is needed. With higher nitrate there is a proximately corresponding suppression of phosphate absorption, so that it becomes necessary to apply phosphate. 3. The required level of nitrate nutrition, which varies with opportunity for carbohydrate accumulation, is intimately associated with potassium requirements. Under field conditions i...
TL;DR: The long postinductive photoperiod employed in these experiments appears to have played a significant role in bringing about the degenerative changes observed and in suppressing the development of mature flowers.
Abstract: 1. Three experimental series of Biloxi soybeans were given photoinductive treatments of from two to ten cycles, consisting of 8 hours of natural daylight followed by 16 hours of darkness. After induction, series I and II were placed on cycles of long photoperiod, consisting of 21 hours of light and 3 hours of darkness, and series III on cycles of 16 hours of light and 8 hours of darkness. 2. Three types of controls were employed. One group of plants was kept on long photoperiod. None of these flowered. A second group was kept on natural photoperiod and a third on short photoperiod. These two groups flowered. 3. Floral buds from controls and from the three experimental series were collected progressively in order to obtain various stages in development. In the second and third groups of controls, floral development was normal and meiosis occurred as has been described by previous workers. In all the experimental groups the floral structures developed normally until the differentiation of sporocytes had occ...
TL;DR: Pollen profiles from bogs in the states of Illinois, Indiana, Michigan, and Ohio are figured, and the two general periods of retrogression are assumed to have been due to climatic causes, producing a less favorable water balance.
Abstract: 1. Fifteen pollen profiles from bogs in the states of Illinois, Indiana, Michigan, and Ohio are figured, thirteen of which have not before been published. All but one are in the central deciduous region. 2. The forest sequence in these profiles shows two periods of retrogression. The earlier was a retrogression from fir and spruce to pine. This was followed by a relative increase of beech, ending in a second retrogression, when oak and hickory increased at the expense of beech. Three of the profiles show subsequent increase and retrogression of beech, but this does not appear to have been general. 3. The two general periods of retrogression are assumed to have been due to climatic causes, producing a less favorable water balance. This is considered adequate to explain the presence of xerothermic relicts in the central deciduous region.
TL;DR: Cuttings in media containing maltose, levulose, dextrose, or lactose in place of sucrose responded in the same way to β-naphthoxyacetic or indoleacetic acid as in controls, while Nitrogen-deficient plants also showed a depletion of starch when treated with the growth substances.
Abstract: 1. Indoleacetic or β-naphthoxyacetic acid in lanolin brought about depletion of starch in tomato cuttings kept 6 days in darkness in a mineral nutrient containing sucrose. Similar cuttings, not treated, still had an abundance of starch after 6 days in darkness. 2. Cuttings in media containing maltose, levulose, dextrose, or lactose in place of sucrose responded in the same way to β-naphthoxyacetic or indoleacetic acid. Nitrogen-deficient plants also showed a depletion of starch when treated with the growth substances. 3. Starch was deposited in the root caps of primordia which resulted from treatment with the growth substance. 4. Digestion of starch was inhibited in thin sections by aqueous solutions of 0.02 or 0.002 per cent indoleacetic acid, while depletion of starch occurred rapidly in the controls. Lower concentrations of indoleacetic acid were ineffective. On the other hand, 0.02 per cent indoleacetic acid in aqueous solution accelerated the hydrolysis of starch in intact stems.
TL;DR: The activity of indoleacetic, indolebutyric, naphthaleneacetic and certain derivatives has been tested on deseeded Avena coleoptiles and Levulinic acid is completely inactive in the Avena test.
Abstract: The activity of indoleacetic, indolebutyric, naphthaleneacetic, dichlorophenoxyacetic, and naphthoxyacetic acids and certain derivatives has been tested on deseeded Avena coleoptiles Intact as well as the usual decapitated coleoptiles were employed, and both agar and lanolin blocks (and lanolin in unilateral smears) were used as carriers 1 When tested in agar on decapitated coleoptiles, potassium salts of indoleacetic, indolebutyric, and naphthaleneacetic are as active as the free acids Esters of indolebutyric are of about the same activity as the acid; esters of indoleacetic are less active than the corresponding acid; and esters of naphthaleneacetic acid are inactive Indoleacetamide, naphthaleneacetamide, and dichlorophenoxyacetic acid are but slightly active Naphthoxyacetic, its ethyl ester, and naphthoxypropionic acids are completely inactive (although reported by others to be active in the tomato test) 2 When applied in agar to intact coleoptiles, indoleacetic, indolebutyric, and naphthalenea
TL;DR: In very fertile midwestern surface soils and subsoils auxin was found to the extent of about 0.175 micrograms per kilogram of soil (indoleacetic acid equivalents) and in less fertile soils considerably less auxinwas found in the surface horizons and little if any in the second horizon.
Abstract: 1. A proximate method is described for the extraction and assay of auxin in soils. One hundred gm. of soil is shaken at intervals for 48 hours with sufficient limewater to keep the pH between 7 and 8 in a volume of 400 cc. The filtered extract is then concentrated and auxin measured by the standard Avena test. 2. Auxin determinations were made on the two upper horizons of eleven virgin soils representative of four of the great soil groups. In very fertile midwestern surface soils and subsoils auxin was found to the extent of about 0.175 micrograms per kilogram of soil (indoleacetic acid equivalents). In less fertile soils considerably less auxin was found in the surface horizons and little if any in the second horizon.
TL;DR: It is concluded that the immunity of Colchicum results from an extramitotic protection, not from a difference in the mitotic mechanism, and may represent the type of resistance found in organisms which do not naturally contain colchicine.
Abstract: 1. Excised roots of Colchicum cultured in small vials are immune to 1 per cent colchicine. 2. Mitosis in excised roots of C. byzantinum can be partly disrupted by 2.5 per cent colchicine and entirely blocked by 5 per cent. Mitosis in C. autumnale is first disrupted and eventually completely blocked by 10 per cent colchicine. The effects are typical of those produced in other angiosperms. 3. It is concluded that the immunity of Colchicum results from an extramitotic protection, not from a difference in the mitotic mechanism. 4. Chlamydomonas pseudococcus, as judged by the rate of reproduction, is resistant both to colchicine and acenaphthene. This immunity is not specific for colchicine and may represent the type of resistance found in organisms which do not naturally contain colchicine.
TL;DR: Reproductive-vegetative interphases, which may be considered as initial stages in rejuvenation, occurred in two species and the short photoperiods inhibited the vegetative growth of both the long- and short-day species.
Abstract: 1. Photoperiodic after-effects were observed in two short-day species (Cosmos bipinnatus, C. sulphureus) and four long-day species (Rudbeckia hirta, Matricaria parthenoides, Centaurea cyanus, Coreopsis tinctoria). Twenty-eight days after planting the seed, the plants being kept under photoperiods unfavorable for reproductive development, they were subjected to from 1 to 20 or 30 induction photoperiods of a length which favored initiation of flower primordia. They were then transferred to photoperiods not favoring such development and retained there for the duration of the experiments. 2. In Cosmos bipinnatus anthesis occurred in some plants exposed to 5-11 short photoperiods, and in abundance in all plants exposed to 12 or more short photoperiods. In the Orange Flare variety of C. sulphureus even the plants retained continuously under long photoperiods eventually bloomed sparsely, but the abundance of flowers increased with an increase in the number of short induction photoperiods. Plants of the long-day ...
TL;DR: Evidence suggests that in all the species of isolated roots investigated, a synthesis of riboflavin took place during culture.
Abstract: 1. The riboflavin content of 1-cm. root tips from aseptically germinated seedlings of five different species has been determined. In each case a similar root tip or tips was cultured in vitro. 2. Riboflavin determinations were done on isolated roots from the stocks thus established. The roots used for assay were bases from which 1-cm. apical tips had been removed and represented samples of the root tissue produced during each weekly culture period. The number of such bases which arose, during culture, from one initial seedling root tip was large; in the case of Datura, for example, over 1000 were actually produced during 63 weeks of culture, and more could have been produced had every branch tip been cultured. With every species, each of these bases contained markedly more riboflavin than the initial root tip from which the root or clone was derived. This evidence suggests that in all the species of isolated roots investigated, a synthesis of riboflavin took place during culture.