bluuebunny/crossref_metadata_2025_split huggingface dataset:
ANALYTICAL STUDIES OF THE GROWTH OF THE ETIOLATED SEEDLING OF AVENA SATIVA
Authors: MER C. L. , CAUSTON D. R. 
Published: May 2006

SummaryThe increased final length of the mesocotyls of intact, etiolated oat seedlings which have been treated with carbon dioxide, sucrose or ethanol, results from the maintenance of cell division in the nodal meristem. Sucrose and ethanol initially retard the overall rate of mitosis but carbon dioxide, at the concentration used, does not. In contrast with these external effects on the growth of the mesocotyl, variation in cell length with treatment is negligible, hence the extra growth is due directly to the increased number of cells.Illumination or high temperature each reduces mesocotyl length by means of two inhibitory effects, on mitosis and on cell elongation. The cells that respond are of a particular length when treated and they show maximum sensitivity when 0.12 mm long, at which length mitosis normally ceases.The retardation of coleoptile growth by sucrose, or by ethanol, is associated with the presence of fewer cells; carbon dioxide appears not to modify the overall rate of cell division. A subsequent stimulation of mitosis, however, does not occur. The cells of the coleoptile, unlike those in the mesocotyl, increase in length after either illumination or heating. Since the same treatments applied to mesocotyl and coleoptile cells elicit different consequences, cell extension in the two organs is most probably controlled by different processes.
RACIAL DIVERSITY IN CALIFORNIAN PRUNELLA VULGARIS
Authors: NELSON ANDREW P. 
Published: May 2006

SummaryTwo sequential common garden studies of Californian Prunella ‐culgmis subsp. lanceolata have revealed the existence of a first‐year flowering low‐elevation race adapted to mild winters and a second‐year flowering montane race adapted to severe winters. Characteristics of habit and growth rate provide for the recognition of coastal and inland forms within the low‐elevation race and Cascade and Sierran forms within the montane race. The distribution of these four racial forms in California can be correlated with climatological features. Clinal variation correlated with latitude and elevation can be demonstrated within each form. A sequence by which the four forms might have evolved is postulated. Comparison of the results obtained with published accounts of variation in European P. vulgaris and other Californian species suggests that modes of infraspecific variation in California and Europe may be more comparable than previous studies would indicate.
ELECTROPHORETIC MOBILITIES OF FORMIC AND GLUTAMIC DEHYDROGENASES IN THE FABACEAE: A SYSTEMATIC SURVEY
Authors: THURMAN D. A. , BOULTER D. , DERBYSHIRE E. , TURNER B. L. 
Published: May 2006

SummaryThe albumins extracted from the seeds of a number of different species of the Fabaceae have been subjected to disc electrophoresis on acrylamide gel. Both formic and glutamic dehydrogenase activities were readily detectable on the gels for ninety of the 103 species examined and one or other of the dehydrogenases on gels of the remaining species.The mobility values of the dehydrogenases varied among the different taxa examined. The more morphologically homogeneous the taxon the less variable were the enzymic data of the species within it, thus within the Vicieae, Trifolieae, Loteae and tribal groupings of Bentham's Phaseoleae species had more nearly similar formic dehydrogenase mobilities than did species of the Podalyrieae and Genisteae (sensu lato).Before any taxonomic conclusions can be drawn a much more extensive survey is necessary; however, sufficient correlations were observed between formic dehydrogenase mobilities and the globulin data of the previous paper to indicate the potential usefulness of this method in systematic studies.
STOMATAL RESPONSES TO CHANGES IN CARBON DIOXIDE CONCENTRATION IN LEAVES TREATED WITH 3‐(4‐CHLOROPHENYL)‐1, 1‐DIMETHYLUREA
Authors: ALLAWAY W. G. , MANSFIELD T. A. 
Published: May 2006

SummaryAn inhibitor of photophosphorylation, 3‐(4‐chlorophenyl)‐1, 1‐dimethylurea, was supplied to detached leaves via their petioles. The stomata partly closed after the inhibitor had entered the lamina but opened again if the intercellular spaces were flushed with air free of carbon dioxide. It is suggested that the closing movement was a response to the accumulation of carbon dioxide in the intercellular spaces, following the inhibition of photosynthesis. The re‐opening after removal of carbon dioxide demonstrated that stomata could open while photophosphorylation was strongly inhibited. The conclusions from these experiments are discussed in relation to a recent hypothesis of the stomatal mechanism.
MORPHOLOGY OF THE NECTARY IN PROTEACEAE
Authors: RAO C. VENKATA 
Published: May 2006

SummaryA comprehensive study of the comparative morphology, anatomy and histology of the nectary in all genera of the Proteaceae was made and the trends in its evolution are discussed. The nectaries in some abnormal flowers of Hakea laurina and Buckinghamia celsissima are also described. The variations in shape of the nectary in the family (and sometimes within a genus); the diversity in its position, either on the thalamus, stipe or floral tube; its position always within the tepal‐stamen whorl; the anatomical and histological features and comparative morphology, all point to the nectary being an enation and not a modified or reduced corolla as previous investigators thought.
THE CROP RESPIRATION RATE OF TULIPS
Authors: REES A. R. 
Published: May 2006

SummaryThe shading methods developed by Watson and Hayashi (1965) for differentiating the photo‐synthetic and respiratory components of net assimilation rate were used on a field scale for estimating the respiratory losses in a tulip crop. By selecting a period in the plant's life which may be described by a linear regression, variation due to weather in growth rate under different sfiading treatments may be averaged.The mean growth rates under each shading treatment may in turn be fitted by a regression line whose intercept with zero light estimates respiration rate, A value of 20% of gross crop growth rate was arrived at; this agrees closely with previous estimates of dry weight losses in bulb crops before emergence.
POLLEN ANALYSIS OF A PEAT FROM THE ISLAND OF CANNA (INNER HEBRIDES)
Authors: FLENLEY J. R. , PEARSON M. C. 
Published: May 2006

SummaryTwo complementary pollen diagrams from Canna show a forest history similar to that found elsewhere in north‐west Scotland, but the NAP values are unusually high. A late‐glacial may possibly be present.
ECOTYPE DIFFERENTIATION IN TEUCRIUM SCORODONIA WITH RESPECT TO SUSCEPTIBILITY TO LIME‐INDUCED CHLOROSIS AND TO SHADE FACTORS
Authors: HUTCHINSON T. C. 
Published: May 2006

SummaryA study has been made of populations of Teucrium scorodonia from Britain and Europe. Edaphic ecotypes have been found to occur with respect to lime‐induced chlorosis. Chlorosis‐susceptible populations were found to be from acidic and non‐calcareous sites whilst chlorosis‐resistant populations were invariably from calcareous sites. The severity of the chlorosis and the retardation of growth in the laboratory suggests that in the field chlorosis‐susceptible populations would be at a great disadvantage compared with resistant ones, on many calcareous soils. In limited field‐experiments, however, seedling failure was found to be due to catastrophic effects such as drought, frost and animal depredation which eliminated both green and chlorotic seedlings. It was found, however, that seedlings of populations from shaded habitats had considerably larger cotyledons than had those from unshaded habitats. This was also true under controlled conditions, irrespective of the shade and nutritional regime given. The seedlings with large cotyledons formed their leaves more rapidly than did those with small cotyledons. Other morphological differences occurred which also appear to be of an adaptational nature. These differences were independent of the soil types from which the populations originated. A study of populations from within a very small area indicated that ecotypic differentiation can take place rapidly and precisely within such an area.
BRYOPHYTES AS INDICATORS OF AIR POLLUTION IN THE TYNE VALLEY
Authors: GILBERT O. L. 
Published: May 2006

SummaryDetailed mapping and recording have shown that many of the commonest bryophytes in Northumberland are totally absent from a large part of the Lower Tyne Valley. The affected area is centred on the coalfield where scattered colliery towns, burning pit heaps and the huge conurbation of Newcastle upon Tyne lie. Emphasis is laid on sulphur dioxide pollution being responsible. Two anomalous situations where sensitive species are found growing well inside their normal limit were investigated. It appears that shelter has a greatly modifying effect in reducing SO2 (but not smoke) levels and that a high pH influences the degree of ionization and rate of oxidation of SO3= so as to favour survival. Protonemata appear to be more sensitive than mature gametophytes.Most bryophytes cannot exist when the average winter concentration of SO2 exceeds 50 μg/ m3 or 0.01 ppm.
SOME ASPECTS OF THE RELATIONSHIP BETWEEN SHADE AND FUNGAL PATHOGENICITY IN AN EPIDEMIC DISEASE OF PINES
Authors: READ D. J. 
Published: May 2006

SummarySome of the environmental factors predisposing Corsican Pine to an epidemic disease known as dieback were studied. The disease is most prevalent on north‐facing slopes, while south‐facing slopes are normally unaffected. Trees on north‐facing slopes produce poor height growth and those showing the poorest growth eventually succumb to the disease. A characteristic feature of the diseased slopes is the absence of sunlight in winter. Disease symptoms appear in this period of sun shadow. The effect of shade on disease susceptibility was therefore investigated. Large increases of infection by Brunchorstia pinea were found after 2, 4, 8 and 12 weeks artifical shading.Artificial shading caused reduction of the soluble carbohydrate content of the buds. Diseasesusceptible buds on north‐facing slopes had comparable low carbohydrate contents, while the levels in resistant buds on south aspects were significantly greater.Soluble carbohydrate content at the end of the growing season was found to be similar in both aspects, but there was a steady decrease through the winter on the north‐facing slope until by January the content was considerably lower than that on the south aspect.Dieback is therefore believed to be caused by fungal attack following loss of respiratory substrate during a prolonged period of low light intensity. Factors such as low growing season temperature and high humidities play a subsidiary role by reducing host vigour and increasing the fungal population.
LICHEN PHYSIOLOGY
Authors: RICHARDSON D. H. S. , SMITH D. C. 
Published: May 2006

SummaryThe main carbohydrates which incorporate 14C during photosynthesis in Xanthoria aureola are ribitol, mannitol, arabitol and sucrose. Ribitol is the first product to accumulate 14C in substantial amounts, and it appears to be produced by the alga. Ribitol is also the main form in which carbohydrate moves from alga to fungus. Entry of [14C]ribitol into the fungus during photosynthesis could be prevented by addition of 1%12C‐pentitols to the medium. In short‐term photosynthesis experiments, incorporation of 14C into mannitol is relatively small, and none is detectable in arahitol. However, in long‐term experiments, more 14C eventually accumulates in mannitol than in other carbohydrates, and [14C]arabitol can also be detected; the delay before appreciable accumulation of 14C occurs into mannitol and arabitol is consistent with their being fungal products. Sucrose never incorporates much 14C, but its early appearance in photosynthesis suggests it is an algal product. The rate of movement of a pulse of 14C between the symbionts of X. aureola is much slower than in Peltigera polydactyla.
NUTRITIONAL REQUIREMENTS OF THE EDAPHIC ECOTYPES IN MELILOTUS ALBA MEDIC.
Authors: RAMAKRISHNAN P. S. 
Published: May 2006

SummaryThe present study deals with the nutritional requirements of the two edaphic ecotypes—(i) the ‘calcareous’, growing on a calcareous soil and (ii) the ‘acidic’, growing on an acidic soil. The germinability of the seeds was found to be inherently different for the two populations. The seeds of the ‘acidic’ population were found to do better in an acid medium and the reverse was found to be the case for the ‘calcareous’ population. Significant differences were noted with regard to the accumulation of calcium and other nutrients under different calcium levels and pH conditions. The ‘acidic’ population always showed a better accumulation of calcium, except at high calcium levels; it also showed a greater ability to accumulate other nutrients like potassium and phosphorus. The adaptive significance of such a behaviour is discussed. A differential response to phosphorus was noted between the two populations, the ‘acidic’ type showing an improved growth yield at higher phosphorus levels whilst that of the ‘calcareous’ type was insensitive. For the same level of phosphorus in the medium, phosphorus accumulation decreased for the ‘acidic’ type at pH 7 in a calcareous medium compared with accumulation in a non‐calcareous medium. For the ‘calcareous’ population, accumulation improved in an alkaline medium. Whilst the accumulation of phosphorus was little affected by change in phosphorus concentration in the medium for the ‘calcareous’ population, the ‘acidic’ type showed improved accumulation with increase in phosphorus level in the medium. The significance of these effects is discussed and it has been shown that besides the direct role of calcium itself, pH with the accompaniment of changes in the availability of phosphorus could be responsible for the restriction of these ecotypes to their respective habitats.
CHLOROPLAST MORPHOLOGY AND FINE STRUCTURE IN BRITISH FUCOIDS
Authors: EVANS L. V. 
Published: May 2006

SummaryChromatophores, principally from eggs, of representatives of the seven genera of the Fucales found in Britain were investigated with the electron microscope and the results are presented here.The chromatophores are bounded by two pairs of membranes inside which lamellations consisting of three or four non‐cohering thylakoids are embedded in a stroma. The stroma of some genera is extended into a simple projecting, stalked pyrenoid and the inner pair of membranes (chromatophore envelope) loop back on themselves to form a covering also to the pyrenoid. The outer pair of membranes (chromatophore E.R.) take no part. Alternatively, two pyrenoids in close proximity, enclosed by a double looping of the chromatopbore envelope, may be found; they lie one above the other either facing in opposite ways or at right angles to each other. More rarely, two widely separated pyrenoids may be found.Pyrenoids of this sort do not occur in association with the egg chromatophores in the Fucaceae (Fucus, Ascophyllum and Pelvetia), but they do occur in the eggs (but not in thallus cells) of members of the Cystoseiraceae (Bifurcaria and Cystoseira), with the exception of Halidrys, and in the Himanthaliaceae (Himanthalia). These pyrenoids are regarded as rudimentary, and as representing a stage close to total eclipse.Pyrenoids in such a natural group are suggested to have phyletic value, their presence being thought to be indicative of greater antiquity than their absence. Hence members of the Fucaceae are thought to be more specialized than members of the Cystoseiraceae. This statement is discussed in relation to earlier results (Manton, 1964, etc.) where the Cystoseiraceae were found to have other kinds of primitive features, and the Fucaceae other kinds of advanced features.
THE MECHANISIM OF FRUCTOSAN METABOLISM IN HIGHER PLANTS AS EXEMPLIFIED IN HELIANTHUS TUBEROSUS
Authors: EDELMAN J. , JEEEORD T. G. 
Published: May 2006

SummaryThe physiological behaviour of the fructose polymers, which are the sole carbohydrate reserve in Jerusalem artichoke tubers, is briefly described. It is suggested that certain enzymes which have been isolated from this tissue can account for these changes, and a theory of their integrated action is put forward: this involves the trisaccharide IF‐fructosylsucrose, widely found in fructosan‐containing tissues, as a key intermediate, and the enzyme which produces it from sucrose as a controlling biochemical factor. Sucrose itself, both as a substrate and by its direct effect on the other enzymes, also acts as a major means of control. The hypothesis does not involve sugar phosphates or nucleotide sugars, and seems to be applicable to other plants which contain fructosans.
A THEORETICAL STUDY RELATING THE CONCENTRATION AND DIFFUSION OF OXYGEN TO THE BIOLOGY OF ORGANISMS IN SOIL
Authors: GRIFFIN D. M. 
Published: May 2006

SummarySome components necessary for the eventual construction of a general model relating the concentration and diffusion of oxygen to the ecology of soil organisms are elaborated from biochemical and physical data and concepts. From the analyses and discussions presented, tentative conclusions can be drawn concerning some of the factors involved in the relationship between oxygen and soil ecology.For roots, bacteria and fungi, most oxygen is taken up through the cytochrome system. Little error is introduced by neglecting the rate of uptake by other terminal oxidases. The rate of diffusion to cells is thus a direct consequence of uptake by the cytochrome system. Oxygen uptake by individual cells will not be affected until the concentration at the sites of the terminal oxidases is of the order of 1 × 10−6to 1 × 10−7M.In many species, the rate of respiration of single fungal hyphae or single bacterial cells will be limited at low external oxygen concentrations by the rate of diffusion of oxygen to the respiratory sites through membranes, walls and sheaths external to those sites. An increase in concentration of oxidase at limiting oxygen concentrations may be ecologically significant in micro‐organisms. The rate at which oxygen diffuses radially through roots with a high respiration rate will often restrict the total rate of oxygen uptake. The centres of such roots will tend to be anaerobic under some field conditions and the situation is likely to be aggravated by root infection and by the presence of some organisms in the rhizosphere. Most roots will be adversely affected at oxygen concentrations higher than those required to adversely affect micro‐organisms on the root surface. The oxygen status of roots will be greatly modified if longitudinal diffusion of oxygen through intercellular spaces that are gas‐filled is considerable.The evaluation of the critical oxygen characteristics in field studies is fraught with difliculties largely associated with specifying the diffusion path of oxygen through the soil to the organ and with obtaining accurate measurements of either oxygen concentration or oxygen flux at the surface of the organ. Use of the platinum micro‐electrode to measure flux can probably give only empirical results but appears to be of practical use where a statistical approach can be used.In some organisms, the major effect of reduced oxygen concentration may well be on the synthesis, or absorption, of some metabolite and not be linked directly to the cytochrome system. Such an organism may be adversely affected by a relatively small reduction in the oxygen concentration and would thus be an exception to the general arguments presented in the article.
EFFECTS OF SEED TREATMENTS WITH GIBBERELLIC ACID ON SUBSEQUENT GROWTH OF SOME EUCALYPT SEEDLINGS
Authors: BACHELARD E. P. 
Published: May 2006

SummaryGermination of seeds of Eucalyptus regnans and E. pauciflora in 50 mg/1 gibberellic acid markedly affected seedling growth. These effects included: stimulation of leaf production and shoot extension growth; slight reduction of root growth; alteration of the root/shoot ratio, and leaf shape; reduction in total dry weight and leaf thickness. Gibberellic acid affected leaf growth through reduced cell division.Stimulation of growth of E. camaldulensis hypocotyl by seed treatment with gibberellic acid could also be attributed to changes in cell division. No evidence of interaction between gibberellic acid and auxin was obtained.These results are discussed in relation to effects of gibberellic acid on other plants and tissues, and it is suggested the responses are explicable in terms of mobilization of food reserves.
NUTRITIONAL REQUIREMENTS OF THE EDAPHIC ECOTYPES IN MELILOTUS ALBA MEDIC.
Authors: RAMAKRISHNAN P. S. 
Published: May 2006

SummaryThe differential tolerance of the calcareous and acidic populations of Melilotus alba Medic, to toxic levels of aluminium and manganese was studied since the availability of these micro‐nutrients is very much dependent upon the pH of the soil. The reduction in the growth yield at toxic levels of aluminium was more pronounced in the case of the calcareous population and at such high levels the acidic type had a significantly higher yield. Only the calcareous population showed symptoms of toxicity due to excess aluminium and it consisted of chlorotic spots on the leaves, particularly the lower ones. The growth yield of the calcareous population was markedly affected by toxic manganese levels in the nutrient solution; the plants were stunted in growth with highly chlorotic leaves, the leaf blades were cupped and the margins of the leaves were crinkled. On the other hand, though the growth yield of the acidic type was also reduced to a lesser degree, the plants did not show any visual toxicity symptoms. At toxic levels of manganese and aluminium, the uptake of other nutrients such as calcium, potassium and phosphorus was more adversely affected in the case of the calcareous than the acidic types.It was concluded that the greater tolerance to aluminium and manganese toxicity of the acidic population is partly responsible for its occurrence in acid soils and the absence of the calcareous population from acidic habitats.
EARLY PLEISTOCENE DINOFLAGELLATES FROM THE ROYAL SOCIETY BOREHOLE AT LUDHAM, NORFOLK
Authors: WALL DAVID , DALE BARRIE 
Published: May 2006

SummaryA more complete account is presented of the ‘hystrichospheres’, both indigenous and recycled, originally found by West (1961) during his palynological investigation of Early Pleistocene marine sediments penetrated by the Royal Society Borehole at Ludhatii, in Norfolk, England. The commonly encountered ‘hystrichosphere’ types of West are identified as x=Operculodinium israelianum (R.)W., y=Tectatodinium pellitum W. and z = Leptodinium mulliplexum sp. nov., while it is probable that a collection of Hystricliospliaera species comprise West's category ‘hooked‐Hystrix’. The majority of these organisms are fossilized gonyaulacid and protoceratioid dinofiagellate resting cysts (spores). These dinoflagellates form five facies‐associations in this sequence. The palaeoecological significance of their distribution is discussed with special concern to palaeoclimates and the future use of dinofiagellates in Quaternary stratigraphy.
A LOWESTOFTIAN LATE‐GLACIAL FLORA FROM THE PLEISTOCENE DEPOSITS AT HOXNE, SUFFOLK
Authors: TURNER C. 
Published: May 2006

SummaryA Late Lowcstoftian macroflora is described from a new stratum at Hoxne, Suffolk, underlying the Pleistocene lacustrine beds investigated by West (1956). The flora is very similir in aspect to other ‘full‐glacial’ floras described from Gipping and Weichselian deposits in Southern Britain.
ELECTROCHEMICAL POTENTIAL GRADIENTS OF IONS IN AN AQUATIC ANGIOSPERM, POTAMOGETON SCHWEINFURTHII (BENN.)
Authors: DENNY P. , WEEKS D. C. 
Published: May 2006

SummaryThe concentrations of the major ions present in mature leaves of Potamogeton schweinfurthii and its natural pond waters were measured, together with membrane potential differences between the interior of leaf cells and the pond waters. Simple electrochemical interpretation of the data suggests active import of chloride, phosphate and sulphate, and active export of potassium and sodium ions. Calcium and magnesium ions may enter very slowly passively but may also be actively exported.