bluuebunny/crossref_metadata_2025_split huggingface dataset:
STUDIES IN POTENTILLA L.
Authors: SMITH GORDON L. 
Published: May 2006

SummaryField populations of Potentilla crantzii in the British Isles are often remarkably uniform morphologically within themselves. Purely vegetative spread seems to be very restricted, and populations consist of discrete individuals, presumably established from seed. The mechanisms involved in reproduction by seed have been investigated in three Scottish topodemes. Crosses between P. crantzii as female parent and P. tabernaemontani, P. arenaria and P. aurea as pollen plants yielded progenies which were quite uniform and which resembled P. crantzii morphologically. The mechanism of maternal inheritance in representatives of these topodemes has been elucidated cytologically. Plants from Ben Lawers and Inchnadamph differed significantly in their embryology from P. tabernaemontani previously investigated. Female meiosis was observed in all stages, but the products degenerated without exception and unreduced embryo sacs arose by diplospory. In the third topodeme from Creag an Dail, there was no sign of meiosis beyond the synapsis stage and embryo‐sacs were aposporous in origin. No plants produced seed without prior pollination. Although, in emasculated flowers, the autonomous division of the egg cell formed embryos, endosperm was always lacking. The continued development of embryos is dependent on endosperm and consequently no mature seed is produced. One chromosome count in endosperm after pollination suggests that endosperm formation is the result of a genuine fertilization rather than merely stimulation by the pollen.
AMINO‐ACID METABOLISM IN GERMINATING SEEDS OF VICIA FABA L. IN RELATION TO THEIR BIOLOGY
Authors: BOULTER D. , BARBER J. T. 
Published: May 2006

SummarySeeds of Vicia faba L. were grown without an external nitrogen supply and the amount of nitrogen in free amino acids, protein amino acids and other soluble nitrogenous compounds determined in the various tissues of ungerminated, 6‐ and 14‐day‐old material.It was found that, on germination, the reserve proteins of the beans were hydrolysed to give at least some free amino acids which were then interconverted and used in the synthesis of new compounds. Glutamine was not formed extensively until after 6 days of growth and the synthesis of this amino acid may be related to the prior onset of photosynthesis which might supply necessary carbon precursors.The proteins of the ungerminated beans were shown to contain a high proportion of nitrogen in basic and dicarboxylic amino acids and during germination major changes occurred during which all these amino acids decreased in amount. Arginine played an important part in the metabolism of the seedlings and the results of preliminary 14C feeding experiments indicate that it may be degraded by a reversal of the ornithine cycle. The decrease in the amount of arginine, other basic amino acids and the dicarboxylic amino acids are discussed in terms of their metabolism and utilization as intermediates in the synthesis of proteins and other nitrogen constituents necessary for the establishment of autotrophic nutrition.
STRUCTURE AND SEASONAL STUDY OF THE SHOOT APEX OF SOME CUPRESSUS SPECIES
Authors: PILLAI S. K. 
Published: May 2006

SummaryThe shoot apices of three species of Cupressus exhibit four zones; the superficial layer, the sub‐apical initials, pith mother cells, and the flanking zone. The superficial layer can be subdivided into the apical initials which contribute by periclinal divisions to the subapical initials below and by anticlinal ones to the surface layer on the flanks. Thus the apical initials form the ultimate source of all the cells of the shoot apex in these species.The subapical initials are composed of a very limited number of cells, and may even be only one cell deep in some apices. The initials give rise to the flanking zone laterally and pith mother cells proximally.The flanking zone exhibits a stratified pattern and is composed of more or less uniform and densely staining cells. The pith mother cells form a very shallow zone. A pith rib‐meristem is absent and the cells mature abruptly into pith cells.During the less active months the apical initials do not exhibit periclinal divisions and hence appear like a tunica. But there is no period of dormancy in the shoot apex of C. sempervirens, of which a seasonal study was made.
THE UPTAKE OF PHOSPHATE BY EXCISED MYCORRHIZAL ROOTS OF THE BEECH
Authors: HARLEY J. L. , LOUGHMAN B. C. 
Published: May 2006

SummaryPhosphate absorbed from KH232PO4 solutions of low concentration by beech mycorrhizas is rapidly esterified. After periods of a few minutes about one‐half of that absorbed is found in organic compounds. Both fungal and host tissues when exposed, after separation, to radioactive phosphate solutions show this ability for rapid esterification. Whole mycorrhizas which had been allowed to absorb KH232PO4 were rapidly dissected in the cold and the labelled phosphate fractions in their host and fungal tissues were separated. In the host tissue 90 % of the 32P was found in inorganic phosphate after half a minute and this percentage fell to a little under 80 % after 10 minutes. The curve of percentage labelling of inorganic phosphate in the host tissue appeared to extrapolate to 100% at zero time. It is concluded that inorganic phosphate passes into the host from the fungus. This result is discussed in relation to previous work on phosphate absorption by mycorrhizas.
FURTHER OBSERVATIONS ON AESTIVATION IN RANUNCULUS REPENS L.
Authors: CUNNELL G. J. 
Published: May 2006

SummaryLarge samples of mature flower buds of Ranunculus repens L., from three different positions on the inflorescence, were collected at two localities near London during the early summer of 1959. From each of the six collections 320 normal flower buds were dissected, 160 with a right quincuncial calyx and 160 with a left quincuncial calyx, and the aestivation of the corollas recorded.Although the corolla aestivation is very variable and all thirty‐two possible arrangements are found in each sample the petal overlaps are not randomly distributed and can be related to the two calyx types. The analysis provides evidence that the aestivation pattern differs with position of the flowers on the inflorescence and that for samples of flowers from any one position on the inflorescence the pattern is similar from site to site and from year to year.Comparison is made with other published work on variable, imbricate pentamerous corollas and the significance of the observations is briefly discussed.
THE EFFECT OF DINITROPHENOL AND OTHER INHIBITORS ON THE UPTAKE AND METABOLISM OF 2,4‐DICHLOROPHENOXYACETIC ACID BY CHLORELLA
Authors: SWETS W. A. , WEDDING R. T. 
Published: May 2006

SummaryThe uptake of 2,4‐D by Chlorella into a non‐diffusible, non‐exchangeable form as influenced by various inhibitors, substrates and environmental factors has been studied. Those factors which tend to increase the rate of glycolysis or to reduce the activity of the TCA cycle result in an increased uptake of 2,4‐D. The addition of exogenous acetate or aspartate also causes an increase in the amount of 2,4‐D retained in the cell.The influence of DNP on 2,4‐D uptake has been given especial attention. Increasing concentrations of this inhibitor at first cause a progressive inhibition of 2,4‐D uptake, which at higher concentrations, is reversed by a substantial stimulation.The data presented are discussed in relation to the hypothesis that the first reaction undergone by 2,4‐D in the cell is one in which acetyl CoA participates. The participation of aspartate in the metabolic process appears to follow that of acetyl CoA and may result in the formation of an aspartyl‐2,4‐D complex.
STUDIES ON THE GERMINATION AND MOISTURE RELATIONSHIPS OF SUGARCANE SETTS
Authors: PANJE R. R. , RAO T. RAJA 
Published: May 2006

SummaryStudies were undertaken to elucidate the moisture relationships in germinating sugarcane setts* and the precise role of moisture in the early stages of germination.It was found that when the controlling effect of the apical meristem was removed by cutting the cane into individual, single‐budded setts, the water in the cane moved into the bud. It appeared that the meristemic cells of the bud (and root primordia) must attain a certain critical water content before they can start to sprout.Increasing the water content of setts increased the moisture in the bud and root primordia until they attained the critical level, when sprouting was hastened. Bud and root primordia appeared to compete for water in the sett. Removal of buds hastened the sprouting of root primordia. When the water content of setts was increased the inhibiting influence of buds on the sprouting of root primordia was nullified.At 96% relative humidity both buds and root primordia sprouted and grew out, but at 85% relative humidity, buds sprouted but root primordia did not. This disparity in the sprouting condition of buds and root primordia appeared to be due to the protective action of the bud‐scales. When the water content of the setts was increased both the buds and root primordia sprouted, but the latter dried up shortly thereafter.Experiments showed that the water in a sett was adequate for the germination of its buds and that, in the early stages, the role of soil water was only indirect.
SOME EVIDENCE OF POPULATION DIFFERENTIATION IN RUBUS IDAEUS L.
Authors: JENNINGS D. L. 
Published: May 2006

SummaryPlants of Rubus idaeus were collected from habitats of contrasting altitudes in Scotland and grown in Dundee. Subsequent observations suggested the presence of population differentiation in respect of time of bud‐burst and plant height, plants from more exposed situations being later to start growth in the spring and producing shorter canes with shorter internodes. The results are discussed in relation to the breeding system and physiological responses of the plants.
POLLEN DIAGRAMS FROM DARTMOOR
Authors: SIMMONS I. G. 
Published: May 2006

SummaryA Seires of pollen diagrams from upland Dartmoor are presented. They cover the Post‐glacial period from early zone IV to the present day but the Late‐glacial is not represented.The extension of forest cover over the region is deduced and an early, pre‐Ulmus decline of forest is noted, preceding more widespread clearance in zones VIIb and VIII The immigration of Alnus is deduced to be more rapid when biotic influences are present. The composition of the past forest is discussed in the light of the present distribution of Quercus spp. In the region and the probable, local presence of Fagus is postulated in zone VIIB and later. The parallelism of the Plantago and Fagus curves lends support to Godwin's suggestion that the immigration of Fagus is bound up with the movements of prehistoric man.
PROTOPLAST STRUCTURE IN SIEVE TUBE ELEMENTS
Authors: THAINE R. 
Published: May 2006

SummaryThe microscopic structure of sieve tube elements was studied in fresh hand sections from Cucurbita pepo, Glycine max and Solanum tuberosum. The sections were stained in aqueous solutions of either iodine (Lugol's) or eosin. Photomicrographs from these preparations show linear cytoplasmic structures attached to sieve plates, and linear files of particles associated with cytoplasmic strands. In addition, phase contrast observations of fresh Cucurbita pepo phloem exudate revealed cytoplasm constituents including membranes, fibrillar elements, 0. 1–0.2 μ in diameter, and mitochondria‐like particles floating free, or associated with the fibrillar elements. Plastids, 5 μ in diameter, also occurred in the fluid exudate, sometimes associated with the aggregates of structural material. Cytoplasmic structures in sieve tube elements and in fresh phloem exudate are interpreted as the remains of damaged transcellular strands.In the transcellular streaming concept of phloem transport, transcellular strands are an essential part of the sieve tube element, and present evidence leaves little doubt that these structures really exist.
A CONTRIBUTION TOWARDS UNDERSTANDING OF ‘THE PRIMITIVE FUCOID’
Authors: MANTON I. 
Published: May 2006

SummaryThe spermatozoids of three genera of Cystoseiraceae (Halidrys, Cystoseira and Bifurcaria) have been investigated electron microscopically with respect to their external morphology, and two of them (Cystoseira and Halidrys) also with respect to their microanatomy for the purpose of comparison with Fucus on the one hand and a brown algal zoospore on the other. Special attention has been devoted to the flagellar ‘root’ which is shown to be the homologue of the proboscis of Fucus and to be present also in the zoospore of Scytosiphon. Comparison between Scytosiphon, Dictyota and the Fucoids suggests that the true function of the flagellar root is not mechanical but metabolic or conductional, perhaps in some relation to respiration or gaseous exchange. The evidence is interpreted as giving strong support to the view that Fucus is not primitive but highly specialized and that Cystoseira has remained closer to an ancestral condition in a number of different characters.
THE TAXONOMIC SIGNIFICANCE OF CERTAIN ANATOMICAL OBSERVATIONS ON ERICACEAE
Authors: WATSON L. 
Published: May 2006

SummaryA review of the classical treatment of Ericaceae reveals how unconvincing are the usual definitions of the major groupings Ericoideae and Arbutoideae. However, a survey of stomatal structure, stomatal distribution and pith structure supports the taxonomic soundness of the main body of the Ericoideae, which are further characterized by their distinctive habit. Calluna is exceptional among Ericoideae in pith structure and stomatal distribution, and differs from the others in various aspects of gross morphology. There is a striking similarity between Calluna and Cassiope, a genus usually placed in the Arbutoideae; and there is little doubt that the two are closely related. These conclusions lead to speculation about the origin and development of the Ericoideae in the minds of taxonomists, and about the mechanism by which closely similar genera become separated at the level of sub‐family.
AN EMBRYOLOGICAL STUDY OF SALOMONIA CANTONIENSIS LOUR
Authors: RAO A. N. 
Published: May 2006

SummaryThe flower development, structure and different aspects of embryology of Salomonia cantonien‐sis are described. Development of the floral parts occurs in acropetal succession. The wall of the anther is composed of three layers of cells. The tapetum is of secretory type with binucleate cells. The endothecial layer develops fibrous thickenings and with the epidermis forms the mature anther wall. The pollen grains are polycolporate, three‐celled at the time of shedding and the majority of them germinate in situ. The ovary is superior and bilocular with a single anatropous bitegmic ovule in each locule. The embryo‐sac develops according to the Polygonum type. The flowers are autogamous and the process of pollination is described. The endosperm is free nuclear to begin with but later becomes cellular. The embryo development follows the Asterad type as in other members of Polygalaceae. Most of the endosperm is used up by the growing embryo. The two‐layered seed‐coat is organized by the outer integument of the ovule. The present observations are discussed with other relevant literature.
A NEW TYPE OF APOGAMY IN FERNS
Authors: BRAITHWAITE A. F. 
Published: May 2006

SummaryStudies on apogamous members of the Asplenium aeihiopicum complex in Africa have shown a marked departure of cytological behaviour from that previously known in apogamous ferns. The sporangial development is characterized by all sporangia producing sixteen spore mother cells each showing complete asynapsis at diakinesis with either 288 or 330–357 chromosomes. The first meiotic division ends in a restitution nucleus which then divides regularly to produce diads of diplospores. This abbreviated meiosis is compared with the cytological phenomena accompanying apogamy in other ferns and with a similar division process known from apomictic Angiosperms. Evidence is presented from the literature which indicates that a similar abbreviated meiosis may accompany apogamy in the Hymenophyllaceae. Little new evidence on either the causal aspect of apogamy or the possible origin of the apogamous forms within the A. aethiopicum complex can be adduced at present.
THE EFFECT OF CATIONS ON THE ABSORPTION OF PHOSPHATE BY BEECH MYCORRHIZAL ROOTS
Authors: JENNINGS D. H. 
Published: May 2006

SummaryPretreatment of beech mycorrhizal roots with relatively high concentrations (10−2 M to 10−1 M) of ammonium, potassium and sodium salts can cause a reduced uptake of radioactivity from phosphate solutions containing 32P. These same salts also decrease the ability of the roots to retain radioactivity already absorbed—the greatest losses occurring at low temperatures. Radioactive phosphorus both in orthophosphate and bound form is lost. Calcium ions have no effect on the absorption of radioactivity but can nullify the effect of the monovalent ions both on the absorption and loss of radioactivity. The results are discussed in relation to other work on cell permeability. It is concluded that the monovalent cations increase a non‐specific efflux of phosphate compounds from the roots which is little affected by metabolism but which can be inhibited by calcium ions. It is also pointed out that these results have important implications with respect to a kinetic analysis of phosphate absorption from solutions of varying strength of a phosphate salt of a monovalent cation. There is evidence that monovalent cations will have a similar effect on phosphate uptake by non‐mycorrhizal tissues.
THE PRE‐PEAT VEGETATION OF THE SOUTHERN PENNINES
Authors: TALLIS J. H. 
Published: May 2006

SummaryPollen counts from the upper layers of the mineral soil underlying deep blanket peat at two sites in the southern Pennines show a varied assemblage of Late‐glacial and montane species such as Armeria maritima, Thalictnim, Juniperus, and possibly Betula nana, existing in zone VI at 550–610 m. This ‘montane’ flora disappears where the pollen spectrum indicates waterlogging of the soil developing as a result of the increased wetness of climate. Peat formation at these two sites appears to begin at the B.A.T., but pollen counts from other sites in the southern Pennines show that peat may have begun to form elsewhere at any time during zone VIIa, depending on local topography. Corylus pollen values show a pronounced maximum at the close of zone VI, and it is suggested that extensive hazel thickets may have formed in sheltered gullies and valley heads; at one of the two sites very high values of fern spores are also encountered in the uppermost layers of mineral soil. The abrupt decline in the fern spore values and equally abrupt changes in values of other pollen types at the level of the peat‐mineral soil junction suggest that there may possibly be a gap in the pollen record at the end of zone VI, resulting from local soil erosion.
TWO FOSSIL DIATOMS FROM THE LAKE DEPOSITS OF THE ENGLISH LAKE DISTRICT
Authors: EVANS G. H. 
Published: May 2006

Summary Melosira distant var. blelhamensis n. var. is described. This has only been found in Post‐glacial deposits. The hitherto uncertain identity of a large Melosira, common in the Late‐glacial and early Post‐glacial lake deposits of the English Lake District, is discussed and it is suggested that its correct name is M. teres Brun.
SECONDARY CORTEX IN THE ARBORESCENT LYCOPODS
Authors: SMITH D. L. 
Published: May 2006

SummaryEarly stages in the development of the secondary cortex in stems of Lepidophloios kilpatrickensis indicate that the tissue originated as a meristematic zone three cells wide. Each cell of the zone underwent periclinal division to form a radial file of cells. It is suggested that in the mature secondary cortex each complete radial file represents the derivatives of three initial cells and that short files represent the derivatives of one, or two, initials.
PLANT GROWTH AND THE AERIAL ENVIRONMENT
Authors: HUGHES A. P. 
Published: May 2006

SummaryPlants were established for 17–23 days in lights of 17–19 cal/cm2/day (≡ 10% summer daylight) using 16 hours fluorescent light in controlled environment cabinets and were then transferred to lower light intensities in the range 1.5–8.7 cal/cm2/day (≡ 0.9–5% summer daylight). The unit leaf rate was linearly related to light intensity over the range 0–20 cal/cm2/day and the compensation point was approximately 0.3 cal/cm2/day. The changes in unit leaf rate were closely followed by marked morphogenetic changes, even in plants growing in light intensities so low that there was scarcely any net gain in weight. Over the dry weight range 6–35 mg low light intensity did not evoke a great increase in leaf area ratio as, over this range in size, the principle cause of increased leafiness was the increase in leaf weight ratio, which is scarcely affected by light intensity. Plants of greater than 35 mg dry weight showed the strong reciprocal relationship between unit leaf rate and leaf area ratio due to the effect on specific leaf area. At very low light intensities the increase in leaf area ratio was not adequate to offset the fall in specific leaf area and the relative growth rate was diminished sharply over the light range from 15 cal/cm2/day to the compensation point for light. The significance of these physiological features for the aut‐Ecology of Impatiens parviflora is discussed.
THE RESPIRATION CLIMACTERIC IN APPLE FRUITS
Authors: JONES J. D. , HULME A. C. , WOOLTORTON L. S. C. 
Published: May 2006

SummaryThe activities of various mitochondrial enzymes in the peel of apples picked before the climacteric peak in respiration (R), were followed throughout the development of the climacteric in storage at 12°C they showed an increase to the climacteric peak and beyond. In pulp tissue the peak values for mitochondrial activity occurred several days before the peak value of R. The soluble enzyme, malic enzyme (M.E.), reached a maximum in both peel and pulp at a point very close to the maximum value of R, while pyruvic carboxylase continued to rise past the climacteric peak.In fruit picked during the development of the climacteric on the tree and stored at 12°C, mitochondrial activity tended to follow changes in R; in the pulp a falling rate of mitochondrial activity probably commenced somewhat before the commencement of a fall in R. M.E. activity increased rapidly on picking in the early stages of the climacteric but little further increase occurred either in peel or pulp when fruit was picked near the point of maximum activity on the tree. This maximum activity on the tree was reached well before the peak in R and corresponded in time with the maximum rate of R ever reached in detached fruit.It is concluded that an increase in activity of M.E. and carboxylase is largely responsible for the climacteric rise in R up to the maximum rate attained in detached fruit, and that the excess respiration above this value ‘on’ the tree stems from other sources.