bluuebunny/crossref_metadata_2025_split huggingface dataset:
ANEUPLOIDY IN YEAST
Authors: COX B. S. , BEVAN E. A. 
Published: May 2006

SummaryHeterozygous white diploid strains of yeast of which one parent is a particular red adenine‐requiring haploid strain often throw a large number of red sectors when they are plated on nutrient agar. It has been shown by genetic analysis and other tests that many of the white spore cultures from one such heterozygote are disomic haploids of constitution n+1 =AD1/ad1. By an extension of the analysis to the red spore cultures from the same heterozygote, it has been shown that some of these are also disomic haploids of constitution n+1 =ad1/ad1. It is concluded that the red haploid strain involved in the heterozygote is a trisomic haploid of constitution n+2 =ad1/ad1/ad1. The genetical significance of the diploid → aneuploid → diploid cycle in a fast multiplying unicellular organism is discussed.
MOVEMENT OF GROWTH REGULATORS IN PLANTS
Authors: McCREADY C. C. , JACOBS W. P. 
Published: May 2006

SummaryThe movement of radioactivity added in the form of indoleacetic acid (as the natural hormone) or as 2,4‐dichlorophenoxyacetic acid (as a synthetic growth regulator) was followed in segments cut from petioles of Phaseolus vulgaris.The movement of 14C added as IAA was strongly basipetally polar, although significant amounts moved acropetally during 24 hours. The velocity of basipetal movement was 6 mm/hour for IAA‐[14C], and was the same for donor concentrations of 5 or 50 μM. The flux increased with increasing concentration in the donor blocks, but a progressively smaller percentage of the applied radioactivity was transported.2,4‐D‐[14C] was found to have very similar transport properties to those of IAA‐[14C], except that its velocity of basipetal movement was much less, namely 1 mm/hour. After correction had been made for the much slower net loss of 2,4‐D from its donor blocks, the acropetal movement of the 14C from the two substances was essentially the same.
THE LIVING WOOD FIBRES OF TAMARIX APHYLLA AND THE CHANGES OCCURRING IN THEM IN TRANSITION FROM SAPWOOD TO HEARTWOOD
Authors: FAHN A. , ARNON N. 
Published: May 2006

SummaryThe viability of the fibres of Tamarix aphylla has been examined by various methods. It has been concluded that the wood fibres retain their living protoplasts for the same period as the wood parenchyma and ray cells, i.e. 16–21 years. The first structures to disappear from the fibres, parenchyma and ray cells were the starch grains (seventh to thirteenth growth ring, as counted from the cambium). The fourteenth to eighteenth growth rings were the last to show positive tetrazolium tests. In the last step before final heartwood production (sixteenth to twenty‐first growth ring), the disintegration of the nuclei occurred.
THE EPIGYNOUS GLANDS OF ZINGIBERACEAE
Authors: RAO V. S. 
Published: May 2006

SummaryRobert Brown's interpretation of the epigynous glands of Zingiberaceae as derived from two out of the three members of an inner androecial whorl, the third member being the posterior functional stamen, has been held as probably correct for many years. Studies on many members of this family, both Indian and foreign, proved that the epigynous glands in this family are special vascularized upward growths from intramarginal portions of the carpels. These portions more or less correspond to two of the three septa of the ovary. The glands are anterolateral in position. Abnormal flowers of many species confirmed the conclusions drawn from normal flowers.
PLANT GROWTH AND THE AERIAL ENVIRONMENT
Authors: HUGHES A. P. , EVANS G. C. 
Published: May 2006

SummaryThe analytical methods developed in the earlier papers of this series are applied to the effects of daylength on the pattern of growth under controlled environmental conditions, with particular reference to ontogenetic drifts. Longer days are found to decrease the leaf weight ratio (8–16 hours by 9%, 16–24 hours by 8%), confirming suggestions from the field observations. Unit leaf rate is nearly proportional to daylength, and if allowance be made for respiration, at a fixed light intensity the daily addition of dry weight per unit leaf area is closely proportional to daylength, in spite of changes in plant form and leaf structure. At a fixed total dry weight of plants grown under fixed conditions of temperature and spectral composition, the specific leaf area is found to be much more closely associated with unit leaf rate than with light intensity or total daily light. Apart from ontogenetic changes, the relationship appears to be influenced by daylength, temperature and the spectral composition of the light. The possibilities of a direct causal relationship are discussed, and the consequences of some anomalous observations are considered. Changing daylength produces changes in unit leaf rate, specific leaf area and leaf weight ratio which have compensatory effects on relative growth rate: at a fixed light intensity an increase of the daylength from 8 to 16 to 24 hours produced increases in relative growth rate of about 20 % and 4 % only. The ontogenetic drifts of dry‐matter content of leaf, stem and root follow their characteristic pattern, higher values being associated with higher unit leaf rates.It is concluded that the growth pattern of the plant is very closely bound up with the rate of accumulation of new material per unit leaf area, over a considerable range of leaf structure. It is noteworthy that Impatiens parviflora was found to make normal growth in constant temperature and humidity conditions with continuous light and flowered normally in 8, 16 or 24 hour days.
THE EFFECT OF AMINO ACIDS ON GROWTH AND SPORULATION OF ASPERGILLUS FLAVUS AND THEIR CARRY‐OVER FOR SUBSEQUENT SPORE GERMINATION
Authors: GROVER RAJENDRA K. 
Published: May 2006

Summary Aspergillus flavus utilized amino nitrogen source better than nitrate, nitrite, or ammonium nitrogen sources. With casein hydrolysate as nitrogen source, optimum growth was obtained at 100 μg N/ml concentration when incubated for 8 days at 24–26° C. Using ten different amino acids singly or in mixture in Czapek's synthetic basal medium at a concentration of 100 μg N/ml, the mycelial yields were higher when the basal medium contained L‐arginine, glycine, DL‐leucine, DL‐methionine or the mixture of ten amino acids, than when casein hydrolysate was used. Abundant sporulation was obtained when the basal medium contained glycine, DL‐leucine or DL‐methionine. Spores harvested from media containing single amino acids germinated very poorly, although spores harvested from media containing casein hydrolysate, when germinated in individual amino acids, showed good germination in β‐alanine, L‐arginine, glycine, DL‐leucine, DL‐methionine and L‐tryptophane. When one of the ten amino acids was omitted from the basal medium, growth response was poor when any of L‐arginine, glycine, DL‐leucine, or DL‐methionine were absent; germination of spores harvested from media devoid of β‐alanine, glycine, DL‐leucine, DL‐methionine or L‐tryptophane was significantly poor. The combination of one or more amino acids did not show any additive effect, but each amino acid seemed to act independently. The carry‐over effects of the amino acids reflected in subsequent spore germination was conspicuous with β‐alanine, glycine, DL‐leucine, DL‐methionine and L‐tryptophane. These five amino acids when used alone or in combination with each other in the basal medium, produced spores which germinated normally; L‐tryptophane seemed to be the most important amino acid among these, as its absence in the medium markedly affected spore germination.
PHYLLOTAXIS AND APICAL GROWTH
Authors: CUTTER ELIZABETH G. 
Published: May 2006

SummaryApical size, phyllotaxis index and the rate of leaf inception were compared in spiral and bijugate specimens of Dryopteris from the same collection and were found to be similar. Apices were laid bare and maintained under observation in the laboratory for periods of up to 9 months; during this time the bijugate specimens became spiral, as previously reported. Exploratory experiments on the bijugate genus Dipsacus indicate that treatment with gibberellic acid leads to increased internodal elongation and a slight increase in the mean angle of divergence. Removal of young developing leaves and leaf primordia leads to an increase in the rates of leaf inception and development. These observations are discussed in relation to the earlier observations and experiments of Snow. The conclusion is reached that while apices with different systems of phyllotaxis may be of similar size and have similar rates of leaf formation and radial growth, progressive changes in various rates of growth may nevertheless lead to changes in phyllotaxis by modifying the relationships between successive leaf primordia. Vertical as well as radial and tangential growth should be taken into account.
THE ANTHROPOGENIC FACTOR IN VEGETATIONAL HISTORY
Authors: TURNER JUDITH 
Published: May 2006

SummaryVertical series of pollen samples from raised bogs at Tregaron, Cardiganshire and Whixall Moss, Shropshire have been analysed and several of the crucial horizons dated by radiocarbon measurements, thus showing some of the vegetational changes which have occurred in the two regions and their approximate duration. These changes are probably the result of human influence during the last few thousand years, and at Tregaron this interpretation is supported by both surface sample analyses and the historical evidence for the changes in the agricultural practices of the area. The different ways and extent to which man modified or determined the vegetation are discussed.
THE INFLORESCENCE OF FAGUS AND CASTANEA, AND THE EVOLUTION OF THE CUPULES OF THE FAGACEAE
Authors: BRETT D. W. 
Published: May 2006

SummaryThe early ontogeny of the female inflorescences of Fagus sylvatica and Costarica satva is described together with some other features of the inflorescences and flowering shoots.The mode of ontogeny of the inflorescences in these species suggests that the two types of cupule are exactly comparable, and that the segments of the cupules (free in Fagus, united in Castanea) are referable to the normal cymose branching of the inflorescence. This is also supported by the vascular organization in the cupules of these species and of Nothofagus. It is, therefore, concluded that the cupule segments in these genera are sterile axes of the next higher order in the dichasium above the flowers they enclose. Thus a single flower is enclosed in a cupule consisting of only two segments (Nothofagus, Castanea), three flowers in a cupule of four segments (Fagus with the primary flower absent, Nothofagus, Castanea), and so on.It has been possible to apply this interpretation to the various forms of cupule occurring throughout the Fagaceae, and by so doing certain important evolutionary trends have been recognized which have suggested a more natural basis for classification and the need to re‐define some genera.The status of the cupule of Fagus as the primitive type is upheld by a general lack of specialization in this genus as regards secondary xylem, cotyledons, some floral characters, and the manner in which the inflorescences are borne. Geographical distribution is briefly considered in this connection.General phylogenetic results of this analysis are expressed in the following proposed subdivision of the Fagaceae:Subfamily I FagoideaeSubfamily II CastaneoideaeTribesi. Castaneaeii. Lithocarpeaeiii. Pasanieaeiv. Querceae
A BIOCHEMICAL APPROACH TO SOME TAXONOMIC PROBLEMS IN THE GENUS COPROSMA
Authors: TAYLOR A. O. 
Published: May 2006

SummaryA limited biochemical investigation of the polyphenols precipitated by lead acetate and present in extracts of Coprosma robusta, C. propinqua var. lattuscula, C. propinqua var. propinqua and interspecific hybrids of these has suggested that:(1) C. propinqua var. latiuscula may have arisen by repeated back crossings of C. propinqua on hybrids of an original C. robusta × C. propinqua var. propinqua swarm.(2) Rapid, quantitative analysis of polyphenols, without the identification of components, could prove a great help in the study of hybridization, introgression, species relationships and phylogeny in the genus Coprosma.
PLANT GROWTH AND THE AERIAL ENVIRONMENT
Authors: HUGHES A. P. , EVANS G. C. 
Published: May 2006

SummaryA comparison was made between the rooting conditions used previously in this series of investigations (sandy loam with added fertilizers) and a mixture of vermiculite, sand and gravel with culture solution. The principal effect of vermiculite was to increase the leaf weight by 25% for a given total dry weight. This was mainly compensated for by a lower root weight. The specific leaf area of vermiculite plants was 5% lower than for plants of comparable size and unit leaf rate in sandy loam. The overall result was a rise of 20% in leaf area ratio. The unit leaf rate was unaffected by the rooting condition so there was a resultant 20% increase in relative growth rate over that in sandy loam. The second comparison was with Red light from magnesium arsenate tubes (6000–7000 Å). Red light from germination gave excessively spindly plants, but plants grown initially for 10 days in Daylight‐white grew well subsequently in Red. There was no effect of Red light on leaf weight/total dry weight distribution. The specific leaf area and relative growth rate were marginally lower. Red light was converted 20% more efficiently on an incident energy/apparent assimilation basis.
POLLEN ANALYTICAL DATING OF A DERBYSHIRE LANDSLIP: THE COWN EDGE LANDSLIDES, CHARLESWORTH
Authors: FRANKS J. W. , JOHNSON R. H. 
Published: May 2006

SummaryAn attempt has been made to use the technique of pollen analysis to establish an upper age limit for a geomorphological feature. The results of the analyses are presented and indicate that local geological events can be traced in the pollen diagram against the background of normal ecological development.
SOME FACTORS AFFECTING THE RATE OF ABSORPTION AND UTILIZATION OF IONS BY STEM SEGMENTS
Authors: PALMER J. M. , LOUGHMAN B. C. 
Published: May 2006

SummaryWhen excised epicotyl segments of Pisum are incubated for periods of up to 24 hours in 0.01 M potassium maleate they exhibit a considerable increase in their ability to absorb and esterify phosphate. In comparison, hypocotyl segments of Gossypium and Helianthus subjected to similar treatments show no change in their ability to absorb and esterify phosphate. The difference in response is attributed to differences between the species themselves rather than to their morphological nature. It is possible to reduce the magnitude of the increase in the rate of phosphate uptake occurring in segments of Pisum epicotyls by increasing the phosphate concentration of the outside medium. This reaction closely resembles that which occurs when slices of potato tuber are similarly treated. In contrast to potato slices, the rate of respiration of Pisum epicotyl segments decreased during the incubation period. The increase in the rate of phosphate uptake is accompanied by an increase in the rate of sulphate absorption and protein synthesis. Other results showed that the rate of phosphate absorption by fresh and incubated tissue is limited by different systems. It would appear that the rate of uptake of phosphate by fresh segments is limited by its rate of diffusion into the tissue, whilst that absorbed by incubated segments is limited by the metabolic activity of the segment.
THE AUXIN, 2,4‐DICHLOROPHENOXYACETIC ACID, AS A REGULATOR OF PROTEIN SYNTHESIS AND SENESCENCE IN DETACHED LEAVES OF PRUNUS
Authors: OSBORNE DAPHNE J. , HALLAWAY MARY 
Published: May 2006

SummaryExperiments on the hormonal regulation of protein synthesis and senescence in detached leaves of Prunus serrulata are described.Senescence is associated with a fall in the content of total protein in the leaf, a loss of chlorophyll and an increase in the soluble nitrogenous fractions. Auxins such as n‐butyl ester of 2,4‐dichlorophenoxyacetic acid (2,4‐D) effectively retard these changes when supplied to leaves at particular stages of growth and development. 2,4‐D is found to stimulate oxygen uptake in young and mature leaves, compared with controls, but has little effect upon oxygen uptake of autumn leaves, while protein levels are maintained by the auxin in freshly detached autumn leaves but not in younger leaves, unless they have already been detached for precise periods of time and considerable protein loss has already taken place.2,4‐D prevents protein loss in autumn leaves by maintaining protein synthesis. The incorporation of [14C] leucine into protein falls by as much as 60% in 7 days in control halves of leaves, but in halves of the same leaves which have been supplied with 2,4‐D, the incorporation of [14C] leucine into protein is sustained at, or above, the original level.It is proposed that auxins participate in the balance of hormonal factors which regulate the metabolism of protein. They would appear to be essential for maintaining the incorporation of amino acids into protein, and at certain stages of leaf development, they would appear to be limiting for the proper functioning of the processes of protein synthesis.The results are discussed in connection with known effects of environment on the auxin content of leaves, and with effects of auxins and other plant growth regulators on protein and nucleic acid metabolism.
A DOUBLE SHELL PLANT GROWTH CABINET
Authors: RORISON I. H. 
Published: May 2006

SummaryThe construction and performance of a plant growth cabinet which stands in an insulated room are described. Its performance does not match that of a closed circuit system, but the uniformity of environmental conditions maintained, despite frequent access, and the ease of access, recommend it to those who need frequent contact with their experimental material. The cost is modest by present‐day standards.
LATE‐QUATERNARY DEPOSITS AT LE MOURA, BIARRITZ, SOUTH‐WEST FRANCE
Authors: OLDFIELD F. 
Published: May 2006

SummaryThe present paper describes pollen‐analytical and stratigraphic evidence and macroscopic plant remains from Full‐, Late‐ and Post‐glacial deposits at Le Moura, a valley bog near Biarritz, South West France. The last part of the Full‐glacial period probably saw the existence of treeless conditions in the area whilst during the Late‐glacial period, pine (including Pinus uncinata) and tree birches spread into the area and forested episodes alternated with periods of park woodland and steppe‐tundra. In the Late‐glacial deposits at Le Moura, indications of hydroseral and terrestial plant successions intermingle in contrapuntal fashion, and only when a detailed palaeo‐ecological analysis of the evidence was carried out did any satisfactory indication of climatic change during the period emerge. The main Late‐glacial episodes closely parallel those from north‐west Europe, a mild forested phase presumably contemporary with the Allerod (zone II) occurs, preceded and succeeded by less wooded, cooler episodes. A pre‐Allerød climatic oscillation of apparently short duration and narrow amplitude is tentatively detected. Among the Full‐ and Late‐glacial plant records, Armeria sp., Cryptogramma crispa, Centaurea cyanus, Empetrum nigrum, Ephedra cf. distachya, Erica tetralix, Euphorbia amygdaloides, Pinus sylvestris and P. uncinata, Polygonum cf. viviparum and Valeriana dioica may be noted. The Post‐glacial record is incomplete, there being a discontinuity in deposition giving rise to the absence of any records from the whole of the period considered equivalent to British pollen zone VIIb, early zone VIII and late zone VIIa. The dominant woodland species throughout the earlier part of the Post‐glacial period are the oaks and pine, with hazel, whilst alder and beech appear towards the top of the diagram. Other mixed oak forest elements are very scarce. Both the strati‐graphic and pollen‐analytical records show that the end of phase P2 (approximately equivalent to British zone VI) at the site was a relatively dry continental period. Whilst the highest levels of the series include records for recently introduced plants such as maize and a species of cedar, earlier pre‐cultural levels include pollen records of Vitis, Olea, Daboecia cantabrica, Erica vagans and Quercus ilex. The biogeographical significance of the plant records and the palaeo‐climato‐logical reconstructions is briefly discussed.
THE ROLE OF ENDOGENOUS GROWTH SUBSTANCES IN THE FRUITING OF UPLAND COTTON
Authors: DALE J. E. , MILFORD G. F. 
Published: May 2006

SummaryTwo acidic growth substances, one promoting, the other inhibiting, straight growth of wheat segments were extracted with diethyl ether from cotton fruit of different ages. The changes in concentration of these substances with time were not related to fruit shedding. The addition of the substances to young fruit did not alter either rate, or level, of shedding and it was concluded that these substances are not controlling abscission of fruit, although they may be connected with fruit development.
PHOTOSYNTHETIC AND RESPIRATORY COMPONENTS OF THE NET ASSIMILATION RATES OF SUGAR BEET AND BARLEY
Authors: WATSON D. J. , HAYASHI KEN‐ICHI 
Published: May 2006

SummaryThe net assimilation rate (E) of a plant population (the mean rate of increase in total dry weight per unit leaf area, measured over a period of 1 or 2 weeks), represents the excess of the rate of photosynthesis of the leaves (P) over the rate of respiration of the whole plants (R), both expressed per unit leaf area (E=P—R). To determine P, photosynthesis was prevented on some days during the experimental period by shading plants, and the effect on E was measured. The plants were held in a controlled environment to ensure that external conditions affecting photosynthesis were the same on all days and effects on change with age in the rate of photosynthesis were avoided by appropriate distribution of the shading days. With these precautions, E was linearly related to n, when n (the number of days when photosynthesis was permitted in an experimental period of 15 days) ranged from 15 to 9. The regression coefficient b of E on n measures the contribution of 1 day's photosynthesis to E, so the photosynthetic component P of EN,the net assimilation rate when photosynthesis is permitted every day in an experimental period of N days, is given by Nb. The respiratory component, R,is estimated by the difference EN—P, or graphically by extrapolating the regression line to n= 0.This method showed that young sugar‐beet plants had a greater net assimilation rate than barley plants solely because they had a greater rate of photosynthesis of the leaves; the values of the rate of respiration of whole plants for the two species were identical.