bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE EVALUATION AND SELECTION OF CHARACTERS IN ANGIOSPERM TAXONOMY: AN EXAMPLE FROM CROTALARIA
Authors: BISBY F. A. 
Published: May 2006

SummaryThe evaluation and selection of characters are both of great importance in Angiosperm taxonomy. Fifty‐two morphological characters, observed in two hundred and seventy‐three African species of Crotalaria L., are analysed using a taximetric procedure, ‘Character Analysis’, which provides a quantitative measure of their potential taxonomic value, the ‘information contribution’. The characters are listed in descending order of information contribution and compared with the relative importance given to them by Polhill in his previously published orthodox study of the genus. The four characters used by Polhill for his major division are among those highest on the list, and only two of the twenty that he used for the delimitation of sections occur in the lower half of the list.The taxonomic value of a character is dependent on how it is defined. The way in which the information contribution measure can be used in the production of better definitions of poor characters is described, and one successful example of ‘Character Improvement’ is given.The potential value of these taximetric procedures in taxonomic revisions of large genera and families with complex reticulate patterns of variation is discussed.
POLLEN ANALYSIS OF LATE‐WEICHSELIAN DEPOSITS AT CORSTORPHINE, EDINBURGH
Authors: NEWEY W. W. 
Published: May 2006

SummaryThe stratigraphy, pollen and other organic material of deposits at Corstorphine, Edinburgh, have been investigated. These deposits are shown to be of lacustrine origin and represent the three zones, I, II and III of the Late‐Weichselian. Herbaceous dominance is indicated in all three zones, and this was particularly marked during the colder climate of Zones I and III; but in Zone II, warmer conditions are suggested by higher tree‐pollen frequencies, with other organic and stratigraphic evidence.
EFFECTS OF FRUITING ON THE GROWTH OF APPLE TREES ON FOUR ROOTSTOCK VARIETIES
Authors: AVERY D. J. 
Published: May 2006

SUMMARYWorcester Pearmain apple trees on four rootstock varieties with a range of vigour were grown in pots for 3 years. The effects of fruiting, determined by comparison with deblossomed trees, were qualitatively similar on all the rootstocks. The growth of all parts, particularly the roots, was less on fruiting trees. The greatest differences occurred in trees on the very dwarfing 3426 rootstock which bore the largest crops relative to the size of the tree; their root systems were severely reduced. When differences in fruitfulness were taken into account, the quantitative effects of fruiting on the dry weight increment of the combined perennial parts, and of the roots alone, were apparently the same on all the rootstocks.Trees with low levels of fruitfulness produced less dry matter, including fruit, than deblossomed trees because of lesser shoot growth. Trees of high fruitfulness produced as much, or even more dry matter than deblossomed trees because of increased photosynthetic efficiency.Comparisons of the shoot growth and stem‐to‐root ratios of the deblossomed trees on each rootstock variety indicated that the hypothesis put forward in a previous paper to explain the dwarfing mechanism of M.1X may be valid for 3426 also.
OBSERVATIONS ON THE CYTOLOGY AND SEED‐PROTEINS OF VARIOUS AFRICAN SPECIES OF CROTALARIA L. (LEGUMINOSAE)
Authors: BOULTER D. , DERBYSHIRE E. , FRAHM‐LELIVELD J. A. , POLHILL R. M. 
Published: May 2006

SUMMARYMitotic metaphase plates of fifty‐seven species of Crotalaria have been studied to determine the chromosome number and compare the size and shape of the chromosomes. The predominance of 2n= 16 is confirmed, but 2n= 14 is general in Section Incanae subsection Incanae and the first instance, in the Old World, of 2n= 32 is reported for C. massaiensis. The shorter and thinner types of chromosome seem most common in the apparently more derived groups of the genus, when a recent classification is adopted.Globulins extracted from thirty‐six species (twenty‐four also examined cytologically) and subjected to disc electrophoresis show four recognizable protein‐band patterns. The two major types of pattern show reasonable correlation with the generic subdivisions and a comparable distribution to the major types of chromosome form.Evidence from both lines of investigation suggests that subsections of Incanae should perhaps be raised to sectional rank.
SUGAR CONTENT IN FLORAL AND EXTRAFLORAL EXUDATES OF ORCHIDS: POLLINATION, MYRMECOLOGY AND CHEMOTAXONOMY IMPLICATION
Authors: JEFFREY DAVID C. , ARDITTI JOSEPH , KOOPOWITZ HAROLD 
Published: May 2006

SUMMARYSugars present in the floral and extrafloral exudates from a number of orchid species have been analysed. All contain fructose, glucose and sucrose. Raffinose is the next most common sugar and stachyose occurs less frequently. Cellobiose, gentiobiose, lactose, maltose, melibiose, melezitose and a few large oligosaccharides may also be present. The distribution of these sugars in orchids may have some chemotaxonomic implications. There appears to be no correlation between the sugar content of exudates and orchid pollinators. This would seem to suggest that scent, form and colour are the major attractants to pollinators in orchids. Floral and extrafloral exudates in orchids may also function as attractants for ants which probably feed on them and repel grazers.
PHOTOSYNTHESIS AND ZONATION OF FRESHWATER MACROPHYTES
Authors: SPENCE D. H. N. , CHRYSTAL JEAN 
Published: May 2006

SUMMARYThe mean, range and standard deviation are given of the depths of water above the soil surface in which a number of Potamogeton species occur in Scottish lochs. Sun leaves of these species were produced in unscreened containers in a glasshouse and their rates of net O2 production were measured at irradiances of from 1.34 to 7.08 cal/cm2/hour in a Warburg apparatus, using Warburg buffer no. 11 as bathing solution. Using only leaves of species of which the rates appeared to be unaffected by buffer solution during the short experiments, it was shown that the shade tolerance of these leaves is correlated with the natural depth distribution of the species. This valid contrast in inherent photosynthetic response between some deep water species (e.g. P. praelongus, P. obtusifolius) and some of shallow water (e.g. P. polygotiifolius) indicates that light may be as important as substrate or competition in controlling the zonation of freshwater macrophytes.
PHOTOSYNTHESIS AND ZONATION OF FRESHWATER MACROPHYTES
Authors: SPENCE D. H. N. , CHRYSTAL JEAN 
Published: May 2006

SUMMARYComparison is made of the photosynthetic response of leaves produced in a glasshouse in unscreened (sun) and screened (shade) conditions, from two species rooted in significantly different depths of water; the shallow‐water Potamogeton polygonifolius, a ‘sun’ species and the deep‐water P. obtusifolius, a ‘shade’ species. Their rates of net O2 production at various irradiances and of O2 uptake were estimated, and chlorophyll content (a + b), specific leaf area (SLA: cm2 leaf area per mg leaf dry weight) and leaf thickness were measured.Of the curves of rate of net O2 production/cm2 leaf area and light intensity, only that of shade obtusifolius was light‐saturated, and lines of best fit were applied to the remainder, which also had high values of r. Slopes were significantly steeper in the order sun obtusifolius shade polygonifolius sun polygonifolius. Under comparable growing conditions, the mean SLA of obtusifolius was twice that of polygonifolius, the range of the two species was mutually exclusive, and that of obtusifolius was narrower than that of polygonifolius, SLA was inversely correlated with the slope of the line of best fit of each leaf‐type.Only at 0.22 cal/cm2/hour did shade obtusifolius have a significantly higher net rate than sun polygonifolius. From calculation of relative rates of photosynthesis/cm2 leaf area, maximum energy yield, φ0, and total CO2 uptake/mg chlorophyll, at 0.22 cal/cm2/hour, of sun and shade leaves of both species, it is shown that P. obtusifolius had a rather similar photochemical capacity to P. polygonifolius; indeed its φ0 was lower.From these facts, increased SLA and reduced respiration and leaf thickness, we conclude that a higher net photochemical capacity/unit area of shade leaves and shade species of Potamogeton in low irradiances (c. 1% summer daylight) is achieved by lowered respiration rate/unit area which itself may result from reduction in leaf weight/unit area. Perhaps the limitation of net photosynthesis in shade species at higher irradiances is a function in a species like P. obtusifolius of its inability to reduce SLA, thicken its leaves and hence increase its capacity to absorb light.
FIXATION OF NITROGEN IN TWO AFRICAN SPECIES OF MYRICA
Authors: BOND G. 
Published: May 2006

SummaryBy means ofgrowth experiments and 15N tests on whole plants and their parts, it is shown that the root nodules present on Myrica cordifolia and M. pilulifera fix atmospheric nitrogen to an extent which suffices to sustain good growth of the plants in a rooting medium free of combined nitrogen. Thus the nodules have the same properties and physiological significance as the nodules of M. gale and M. cerifera. The possession of this internal source of combined nitrogen doubtless explains in part the ability of M. cordifolia to flourish on sand dunes.
THE ULTRASTRUCTURE OF LICHENS
Authors: JACOBS J. B. , AHMADJIAN V. 
Published: May 2006

SummaryHigh resolution radioautography was used to demonstrate the transfer of carbon compounds from alga to fungus in Cladonia cristatella Tuck. After a 24 hour incubation with 14CO2, most of the label appeared in the algal chloroplast around the pyrenoid and in starch. The label in the fungus was present largely in the hyphal wall.
CARBOHYDRATE METABOLISM IN CHAETOMIUM GLOBOSUM
Authors: ADOMAKO D. , KAYE M. A. G. , LEWIS D. H. 
Published: May 2006

SummaryThe uptake of the hexoses, glucose, fructose and mannose, by resting mycelium of Chaetomium globosum results in synthesis of the reserve carbohydrates, trehalose and glycogen, which form, respectively, 5–7% and 12–23% of the dry mycelium. Glucose is the only free reducing sugar present in detectable amounts. The presence of galactose and mannose in acid extracts of mycelium suggests that polymers of the galacto‐mannan type are important components of the cell wall. Mannitol forms a very small proportion of the total cellular carbohydrates but its level is two to three times greater in mycelium incubated on fructose or mannose than when incubated on glucose. There is an increase in the level of polyol during starvation of the mycelium as glycogen disappears and glucose accumulates. These observations are discussed in relation to the distribution and metabolism of fungal reserve carbohydrates in general.
STUDIES ON THE SUPPLY OF OXYGEN TO THE ROOTS OF MUSTARD SEEDLINGS (SINAPIS ALBA L.)
Authors: GREENWOOD D. J. , GOODMAN D. 
Published: May 2006

SummaryMost of the requirements of roots for oxygen were met by oxygen from the air entering the leaves and travelling through the plants to the roots in oxygen‐free media. The amount of oxygen supplied in this way decreased proportionately with rise in oxygen partial pressure at the root surface. Although roots offered a considerable barrier to the passage of oxygen out of them, experiments in which transport from the aerial parts was prevented indicated that the roots could obtain almost all the oxygen they required from the surrounding media provided the oxygen partial pressure at the root surface exceeded the low value of 0.05 atmospheres.These results were obtained by means of a new experimental technique which enabled the effect of oxygen partial pressure at the root surfaces on oxygen uptake and root elongation to be studied. It was based on circulating a small volume of nutrient solution around roots in a gas‐free enclosed system sufficiently rapidly for the partial pressure in the solution to be almost the same as at the root surfaces.
THE RELATIONSHIP OF COMPARTMENTATION OF ORGANIC ACID METABOLISM TO BICARBONATE‐ION SENSITIVITY OF ROOT GROWTH IN CALCICOLES AND CALCIFUGES
Authors: LEE J. A. , WOOLHOUSE H. W. 
Published: May 2006

SummaryIt was shown previously that cell elongation in the roots of certain calcifuge grasses was inhibited by concentrations of bicarbonate and malate which promoted cell elongation in related calcicole species. The present paper reports experiments in which [2‐14C]‐acetate was supplied to excised roots of a calcifuge Deschampsia flexuosa and a calcicole species Arrhenatherum elatius. Time course studies of the pattern of [2‐14C] incorporation into the organic and amino acids of the roots indicates an active tricarboxylic acid cycle in both species but differing in that in Deschampsia the respiratory malate pool was more completely compartmented from other malate pools in the cells, whereas in Arrhenatherum a progressive mixing of the malate pools occurred. Treatment of roots with a pulse of [2‐14C]‐acetate followed by exposure to 10 m‐equiv./1 HCO−3 for 3 hours resulted in a substantial modification in the pattern of 14C incorporation from acetate in Deschampsia but not in Arrhenatherum. The results are discussed in relation to the differential effects of bicarbonate on root growth in the two species.
SOME ASPECTS OF POTASSIUM LOSS FROM EXCISED BARLEY ROOTS
Authors: NASSERY H. 
Published: May 2006

SummaryThe process of efflux of potassium from excised barley roots was measured during 2 hours under different conditions of treatment. Under normal metabolic rates a rapid loss of potassium occurs during the first 40 minutes, followed thereafter by a very slow rate of loss. 10−5 M DNP not only increases the potassium loss but also alters the pattern of potassium efflux such that the efflux continues its rapid initial rate for 2 hours. The potassium loss during the rapid phase is metabolically dependent, but is not proportional to the total potassium absorbed. This indicates that under normal metabolic conditions, potassium loss is mainly from the cytoplasmic fraction. 10−2 M CaCl2 reduces the potassium loss more at 25° C than at I° C.
THE EFFECT OF HYDRATION‐DEHYDRATION ON SEED GERMINATION
Authors: BERRIE A. M. M. , DRENNAN D. S. H. 
Published: May 2006

SummarySeeds of tomato and oats were subject to hydration‐dehydration treatments at various times during germination. Desiccation has little harmful effect if carried out before cell division and enlargement has commenced. Some advancement of the onset of germination was apparent due probably to slight changes in the seed covering and also to the initiation of metabolic events which could withstand the dehydration, e.g. the increased protease activity was maintained in the dried seed.Dehydration can be done more than once. The effects are only truly accumulative if the prior imbibitions are of substantial duration.Physical changes associated with hydration are fairly easily reversed but some of the chemical changes beginning in oat within 8–12 hours of imbibition cannot be returned to the original dry seed condition by desiccation. Once embryo growth is apparent, embryo damage of some sort usually results.
THE ROLE OF THE ENDOSPERM IN UPTAKE AND DISTRIBUTION OF EXOGENOUS LEUCINE IN GERMINATING LETTUCE SEEDS
Authors: KLEIN S. , NEGBI M. , WITZTUM A. , ROTHBERG LIORA 
Published: May 2006

SummaryWhen lettuce embryos with their endosperm of two cell layers were germinated in a solution containing [3H]‐leucine, very little was taken up and its incorporation into protein occurred mainly in the endosperm. Uptake and incorporation were higher in isolated endosperms and isolated embryos and more label was found in the embryo than in the endosperm. Germination‐inducing irradiation did not affect the amount or the distribution of the label in the endosperm and the embryo. The results show the existence of a permeability barrier on the outside of the endosperms, and indicate that in experiments with intact seeds the distribution of the incorporated leucine cannot be taken as a measure of the specific synthetic activity of the embryo and the endosperm.
ROUTINE ANALYSIS BY GAS‐LIQUID CHROMATOGRAPHY OF SOLUBLE CARBOHYDRATES IN EXTRACTS OF PLANT TISSUES
Authors: HOLLIGAN P. M. , DREW E. A. 
Published: May 2006

SummaryRetention times for the trimethylsilyl ethers of more than fifty carbohydrates on 2% SE 52 columns and for the acetate derivatives of monosaccharides and polyols on 5% PEGA columns are given. The results of subsequent analyses of the soluble sugars and polyols in representatives of the following plant groups are described: algae (seven spp.), fungi (four spp.), lichen (ten spp.), bryophytes (six spp.), pteridophytes (five spp.) and angiosperm (seven spp.).
POLYMORPHISM IN PSILOCYBE MERDARIA
Authors: WATLING ROY 
Published: May 2006

SummaryAn isolate of the purple‐brown spored agaric Psilocybe merdaria (Fr.) Ricken, which had been collected on Mull, Scotland, was found to be unstable in its morphological characters when in pure culture. Apart from normal fruit‐bodies a series of forms developed, ranging from laterally stipitate to gasteromycetoid ones. The morphological characters of the two extreme forms, before and after several subcultures were made, are described. How these abnormal fruit‐bodies might amplify past and present theories on the origin of the Gasteromycetes is considered. The shape of the basidium in this one isolate was also found to be plastic and several deviations from the typical basidium are described. It is suggested that the origin of at least some types of pleurocystidia should be sought in modifications of the basidium. The use of the basidium as a major character in the classification of the Basidiomycetes is not discredited, but a closer relationship than previously expressed between the different groups of the higher fungi is argued. It is suggested that useful information might be obtained from the further study of teratological forms similar to those of P. merdaria whenever they are found in other higher fungi. In the field aberrant forms are not as rare as might be at first supposed.
SHORT TERM RESPONSES AND CHEMICAL CONTROL OF RIBONUCLEASE ACTIVITY IN TOMATO LEAFLETS
Authors: DOVE LEWIS D. 
Published: May 2006

SummaryRibonuclease (RNase) activity of tomato leaflets increased 3–6 hours after excision in air and then declined to attached leaf levels within 12 hours after excision. Leaflets submerged in a c bar mannitol solution during excision failed to exhibit a significant RNase ‘pulse’ while more dilute mannitol solutions and a dilute nutrient solution failed to suppress this increase in RNase activity; the RNase ‘pulse’ appears to be a response to a disrupted water balance in the leaflet. The RNase response to leaf excision was also reduced by immersing air‐detached leaflets in 0.2 ppm indoleacetic acid (IAA). Kinetin solutions were effective at 2 ppm when leaflets were immersed in kinetin solutions for 4 hours before excision as well as after detachment. Kinetin and IAA also suppressed gradual increases in RNase activity characteristic of tomato leaflet senescence. IAA and kinetin together were somewhat less effective than IAA applied alone. Cytidylic and adenylic acids as well as chloramphenicol were also effective in inhibiting this long term increase in RNase activity.
A NEW METHOD FOR DESCRIBING LEAF SHAPE
Authors: DALE M. B. , GROVES R. H. , HULL VALERIE J. , O'CALLAGHAN J. F. 
Published: May 2006

SummaryA new method for the description of leaf shape is presented, based on an interactive computer program for describing rosette leaves of Chondrilla juncea. In addition to the usual measures of length, breadth and area an alternative description is provided based on a coding of the boundaries of the leaves. The efficiency of the machine‐assisted description is assessed and a comparison of the alternative descriptions provided.
ANALYSIS OF THE POST‐INFECTION GROWTH STIMULUS IN ORCHID MYCORRHIZA
Authors: HADLEY G. , WILLIAMSON B. 
Published: May 2006

SummaryThe sequence of symbiotic infection of Dactylorhiza purpurella protocorms shows that commencing shortly after infection there is a linear increase in length and breadth whereas growth of uninfected protocorms is negligible.From the time when external hyphae make physical contact with epidermal hairs of the host the processes of penetration, infection of the cortex and formation of the first pelotons occupy approximately 29 hours. There is a linear relationship between the number of pelotons and time but the size of protocorms is not directly related to the number of pelotons. Evidence suggests that stimulation of growth can take place before intracellular lysis of the endophyte occurs.In the absence of external nutrients infecting hyphae are rapidly lysed and little or no growth stimulus occurs. The hypothesis is posed that ‘digestion’ of the endophyte is a defence reaction not a pre‐requisite for a growth stimulus and that nutrients are transferred across the living fungus‐host interface and stimulate growth.
THE FUNGUS‐ALGA ASSOCIATION IN THE LECIDEACEAE: AN ULTRASTRUCTURAL STUDY *
Authors: GALLUN MARGALITH , BEN‐SHAUL Y. , PARAN NAVAH 
Published: May 2006

SummaryThe relationship between fungus and alga in three Lecidea species was examined by electron microscopy. The contact between the symbionts ranged from intracellular fungal invasion in the primitively organized thallus to a looser association of wall‐to‐wall attachment in the more highly differentiated growth‐forms.The correlation between the symbiont association and thallus development has been compared with a similar correlation found in the Lecanoraceae.
THE CAUSATION OF THE DIURNAL CHANGES IN NITROGEN FIXATION IN THE NODULES OF ALNUS GLUTINOSA
Authors: WHEELER C. T. 
Published: May 2006

SummaryThe translocation of 14C‐labelled photosynthate to the nodules of first‐year alder plants growing under natural illumination, but at constant temperature, is shown to be a rapid process which results in a maximum influx of new photosynthate at the time of the mid‐day peak in fixation. Analysis of fluctuations in the levels of the main free sugars present in the nodules at different times of day, and a study of the effects of interrupting supplies of photosynthate to the root system by stem ringing, suggests that a substantial part of the nodule carbohydrate is unavailable for fixation and that maximal rates of fixation are only attained when new photosynthates are entering the nodules in quantity. No evidence was obtained for an autonomous element in the mid‐day maximum in fixation when plants were kept in continuous darkness; a fall in acetylene reduction to an insignificant level 24 hours after darkening was accompanied by a fall in nodule sugars—notably in the amount of sucrose present.The rate of acetylene reduction by nodulated roots reached a maximum at about 25° C, and, at this temperature, was some six times faster than at 15° C.
THE EFFECT OF CATIONS ON GLUCOSE UTILIZATION BY, AND ON THE GROWTH OF, THE FUNGUS DENDRYPHIELLA SALINA
Authors: ALLAWAY A. E. , JENNINGS D. H. 
Published: May 2006

SummaryThe effect of sodium and potassium chlorides on glucose uptake by Dendryphiella salina after growth in glucose‐tryptone media of varying cation composition has been studied. The results are explicable in terms of the previous findings on the relationship between glucose uptake and the potassium and sodium content of the mycelium. Other experiments on the effects of potassium and sodium chlorides separately and sodium and calcium chlorides together on growth in a range of glucose concentrations have provided evidence that cations can also influence glucose utilization by providing a source of osmotic pressure within the hyphae alternative to organic solutes.