bluuebunny/crossref_metadata_2025_split huggingface dataset:
POPULATION DIFFERENTIATION IN AGROSTIS TENUIS SIBTH
Authors: BRADSHAW A. D. 
Published: May 2006

SummaryIn order to investigate the physiological differentiation occurring within a species, samples of sixty tillers of a number of populations of Agrostis tennis were transplanted into experimental plots established in various contrasting natural habitats in the neighbourhood of Aberystwyth in central Wales. Two populations were also grown on lead‐contaminated soil. Their performance under the different environments was examined. It was found that:

Populations originating from contrasting habitats differed considerably in their ability to tolerate different extreme conditions. For instance, the growth of lowland populations in the upland plot was seriously affected by winter conditions, and the growth of upland populations in the coastal plot was affected by salt storm spray. The population from a lead mine was able to grow in lead‐contaminated soil, while the population from normal pasture was not. The behaviour of each population could always be related to the environment from which the population originated.
These differences were also found, although on a smaller scale, between populations originating from less contrasting environments.
Populations originating from habitats only a short distance apart showed considerable differences in performance in those cases where the original habitats were markedly different.
Such physiological differentiation was not necessarily accompanied by morphological differentiation. It is likely that this is because the two types of differentiation are in relation to unrelated factors of the environment.

It was concluded that the pattern of physiological differentiation was a graded patchwork similar to the pattern of morphological differentiation previously described.
STRATIGRAPHY AND POLLEN ANALYSIS OF THE RAISED BEACH DEPOSITS AT BALLYHALBERT, GO. DOWN, NORTHERN IRELAND
Authors: MORRISON M. E. S. , STEPHENS N. 
Published: May 2006

SummaryThe development and stratigraphy of the raised beach shingle ridge at Ballyhalbert, on the east coast of the Strangford Peninsula, are described.A pollen diagram from the peat layer buried beneath the beach gravels shows that the lowest of the gravels was deposited towards the close of the Boreal period, namely sub‐zone VIc.The discussion emphasizes that the precise date of the maximum of the marine transgression in Ireland cannot be obtained from present Irish data. However, it is reasonable to accept tentatively that in Ireland, as in England, the maximum arrived during the Atlantic period.
SOME ASPECTS OF THE DEVELOPMENTAL ANATOMY OF THE‘LONG’SHOOT IN LARIX DECIDUA MILL., WITH PARTICULAR REFERENCE TO SEASONAL PERIODICITY*
Authors: FRAMPTON C. V. 
Published: May 2006

SummaryA description is given of the structure and behaviour of the terminal bud of the ‘long’ shoot in Larix decidua Mill, throughout the yearly growth cycle. Within the bud two regions of the new growth, the ‘axial’ and the ‘fascicular’, may be recognized. The capacity of a bud to grow into a ‘long’ shoot depends on the presence within it of the ‘axial’ portion, and is thus determined in the season prior to the opening of the bud. Weaker branches of the tree bear smaller terminal buds in which the ‘axial’ portion is reduced or absent.
A NEW METHOD FOR THE COMPARISON OF POPULATIONS THAT CONTAIN HYBRIDS*
Authors: GAY PETER A. 
Published: May 2006

SummaryOrthodox statistical methods frequently cannot be employed in the analysis of data obtained from natural populations that contain hybrids. The method outlined, which is based upon Anderson's technique of Hybrid Indices, eliminates some of the subjective element that is inherent in that technique and facilitates the comparison and summary description of complex populations that contain hybrids. The variation of these two statistics in various types of population is illustrated and the value and limitations of the method discussed.
RHOSGOGH COMMON, RADNORSHIRE: STRATIGRAPHY AND POLLEN ANALYSIS
Authors: BARTLEY DAVID D. 
Published: May 2006

SummaryA number of stratigraphical sections and four pollen diagrams have been constructed in an attempt to trace the history and development of the area.Together, the pollen diagrams cover a period starting in zone I of the Late‐glacial period and ending in zone VIII. The diagrams are generally of a western type but correspond more closely with the Somerset diagrams than with the Cardiganshire or Shropshire type.Correlation between the stratigraphy and the pollen analysis show that the Common and its immediate surroundings began its development towards the end of the last glaci‐ation when the irregular dumping of drift material led to the impounding of a long, shallow lake. By progressive deposition of material, at first mineral but later organic, the lake basin gradually became filled and the vegetation which covered it passed through the stages of a typical hydrosere to Spagnum bog and Callunetum. At about the time of the Boreal‐Alantic transition the course of the succession, which had until then included Phragmites‐Cladmm fen, became altered and the fen and reedswamp stages are now represented by an impoverished swamp dominated by species of Juncus and Carex.The birchwood‐with‐Phragmites has developed from a lagg vegetation while the birchwood‐with‐Cflmv and the southern birchwood have been formed by the colonization of the bog communities, the former at a comparatively recent date.The most recent of those deposits which have been investigated are the downwash clays which are correlated in the pollen diagram with zone VIII and were apparently produced as a result of forest clearance and increasing wetness of climate.
STUDIES ON THE GROWTH OF EXCISED ROOTS
Authors: STREET H. E. , HUGHES JOYCE C. , LEWIS J. SYLVIA 
Published: May 2006

SummaryTwenty‐one L‐amino acids and the amides L‐glutamine and L‐asparagine have been tested for their effects on the growth of excised tomato roots, by adding them singly to a medium of pH 4.8 containing the standard amount of nitrate. L‐ and D‐cystine were growth‐stimulatory. The amides, L‐aspartic acid and L‐arginine, did not significantly affect growth in concentrations up to 25 mg/1. The other amino acids were, to very differing extents, inhibitory to growth. The inhibitory activity of certain amino acids was greater at pH 6.8 than at 4.8. At this pH low concentrations of L‐arginine enhanced growth. The L‐ and D‐ forms of the amino acids differed in their inhibitory activity.With the exception of L‐glutamine and, to a lesser extent, of L‐asparagine and the natural forms of the dicarboxylic amino acids, all the amino acids tested as sole nitrogen sources for root growth were completely ineffective at both pH 4.8 and 6.8. This applied also to the ‘balanced’ mixtures of amino acids which had only low inhibitory activity when added to a nitrate‐containing medium.“Bacto’ casamino acids (an acid‐hydrolysed casein) was more effective than ammonium as a nitrogen source over the range pH 4.8 to 7.0, but was only as effective as nitrate at pH values close to neutrality.At pH values of 5.3 or above, the growth of excised tomato roots on ammonium was markedly stimulated by the addition of amino‐acid mixtures whose composition was based upon amino‐acid analyses of hydrolysed casein. A mixture of the basic amino acids only was almost as effective as more complex mixtures. At pH 6.8 ammonium plus a suitable amino‐acid mixture supported growth equal to that with the casamino acids. The very poor growth of excised tomato roots supplied with ammonium at pH 4.8 was, however, not significantly enhanced by the amino‐acid additions which were markedly stimulatory at higher pH values, and was inferior to growth with casamino acids at this pH. A high level of root growth cannot yet be achieved at pH 4.8 in the absence of nitrate.
CYTOGENETIG RELATIONSHIPS OF VIOLA LACTEA SM. AND OTHER WEST EUROPEAN AROSULATE VIOLETS
Authors: MOORE D. M. , HARVEY M. J. 
Published: May 2006

Summary1. The interrelationships of five western European violets are determined by examining chromosome pairing in their F1 hybrids. Viola stagnina Kit. (n= 10), V. pumila Chaix. (n= 20), V. canina L. sspp. canina and montana (L.) Fries. (n= 20) and V. lactea Sm (n= 29) belong to the group Arosulatae and Viola riviniana Rchb. (n= 20) is in the group Rosulantes.2. (a) Seven artificial interspecific hybrids were studied and the most frequent meiotic chromosomal arrangements can be summarized as follows: Viola canina × lactea (2n= 49)—2011+91; V. canina × stagnina (2n= 30)—101 + 101; V. canina (sspp. canina and montana) × riviniana (2n= 40)—1011+201; V. lactea × riviniana (2n= 49)—1011+291; V. pumila × canina (2n= 40)—1011 + 201; V. lactea × pumila (2n= 49)—1011+291.(b) V. canina ssp. canina × riviniana and V. lactea × riviniana also had supernumerary chromosomes, derived from their riviniana parent. These varied in number, even between the p.m.c. of a single hybrid plant, which suggests somatic chromosomal irregularity, possibly during premeiotic mitosis.(c) The two hybrids involving V. pumila frequently showed a high proportion of multivalents, as well as ‘clumping’ of the bivalents; the univalents were generally distinct but some tended to show secondary association at M1.3. The genomic constitutions of the species were deduced from the chromosome pairing in the hybrids. The species are seen to be related in a reticulate pattern which is based on the combination of genomes by allopolyploidy. Within this pattern the groups, Arosulatae and Rosulantes, merge into one another, at least one genome being shared by species in each group.4. The affinities and origin of Viola lactea are discussed. It is an allohexaploid deriving two genomes from V. canina. The species carrying the third genome cannot be found in western Europe and it is suggested that, if it still exists, it may be among the diploid Arosulatae in eastern Asia.
AN EFFECT OF GIBBERELLIC ACID ON GIRGUMNUTATION
Authors: McCOMB A. J. 
Published: May 2006

SummaryGibberellic acid causes a marked increase in the amplitude of circumnutation in dwarf pea seedlings. The effect may be detected within 12 hours from the time of treatment. The relation was investigated between the time at which this effect occurred and the time at which increased growth of the shoot was detected.
FLORAL PIGMENTS IN PAPAVER AND THEIR SIGNIFICANCE IN THE SYSTEMATICS OF THE GENUS
Authors: ACHESON R. M. , JENKINS C. L. , HARPER JOHN L. , McNAUGHTON I. H. 
Published: May 2006

SummaryChromatographic analysis of the floral pigments of species of the genus Papaver revealed the presence of cyanidin and pelargonidin derivatives and in addition yellow compounds which were not anthocyanins. The distribution of these pigments among the poppy species supports Fedde's division of the genus into sections, and suggests an affinity between the sections Pilosa and Scapiflora. The pigments of three interspecific hybrids showed the biochemical versatility of the less versatile parent.The anthocyanins of petals and stamens frequently differed and the bases of petals normally contained petal and stamen pigments in mixture. High concentrations of cyanidin pigments were not found in the same floral parts as either yellow pigments or high concentrations of pelargonidin derivatives.
PHYSIOLOGICAL STUDIES OF GERMINATION IN THE GENUS AVENA
Authors: DRENNAN DONALD S. H. 
Published: May 2006

Summary

Changes in fats, sugars and starch have been followed in grains of A. sativa during the first few days in germination conditions.
A decrease in fats and some of the sugars present in the dry grain was evident during the first day; the utilization of starch did not commence until between the first and second days.
It is concluded that the metabolism of the germinating grain is not initially dependent on starch‐derived materials. Fats and some of the sugars are suggested as likely alternatives for respiratory substrates.
The relevance of this to previous studies on the development of starch‐degrading enzymes in germinating and dormant grains of Avena spp. is discussed.
THE EFFECTS OF DAY‐LENGTH ON THE DEVELOPMENT OF THE SPOROPHYTE OF POLYTRICHUM ALOIDES HEDW. AND P. PILIFERUM HEDW.
Authors: HUGHES J. G. 
Published: May 2006

SummaryThe apical meristem of the sporophyte of Polytrichum spp. has been described briefly. The meristem is described as vegetative so long as it continues to contribute cells to the seta: in this vegetative phase the endothecium is a distinct histogen. In the reproductive phase all the cells in the meristem are used in the construction of the sporangium and the onset of this phase is marked by the segmentation of the endothecium from below upwards.Experiments with P. aloides Hedw. and P. piliferum Hedw. indicate that the development of the sporangium, once initiated, is conditioned by seasonal factors, but the transition from the vegetative to the reproductive phase is conditioned by some other factor(s) not identified. When the growth of a sporangium is inhibited by experimental conditions, vegetative growth is not prolonged.
STUDIES ON THE PROTEINS, PEPTIDES AND FREE AMINO ACIDS IN GYSTOGARPIG AND TETRASPORIG PLANTS OF AGARDHIELLA ROBUSTA FROM BOMBAY
Authors: LEWIS E. J. , GONZALVES ELLA A. 
Published: May 2006

SummaryCystocarpic and tetrasporic plants of Agardhiella robusta (Grev.) Boergs., collected from Bombay, were analysed separately for the constituent amino acids in the proteins, peptides and in free state, by using a quantitative paper chromatographic technique. A total of twenty‐four amino acids were detected in them. Qualitative variations occurred between cystocarpic and tetrasporic specimens only in the peptide hydrolysates, and quantitative differences were observed in some individual amino acids in the proteins, peptides and in the free state.
THE ANEMIA ADIANTIFOLIA COMPLEX IN JAMAICA
Authors: WALKER TREVOR G. 
Published: May 2006

SummaryIt has been shown that Anemia adiantifolia, which has customarily been regarded as a uniform species, forms a polyploid series in Jamaica, with diploid, triploid and tetraploid cytotypes. The tetraploid backcrosses to the diploid in the wild to give rise to sterile triploid hybrids. The latter form thirty‐eight bivalents and thirty‐eight univalents at meiosis and this, coupled with the morphological and cytological evidence, indicates that the diploid is one of the parents of the allotetraploid. Distributional studies of the forms in Jamaica from a sample of eighty‐seven plants show that the diploid is the more common form, both numerically and distributionally. Little evidence can be adduced from the morphology of the tetraploid as to its other diploid parent.
SUGAR ABSORPTION BY CHAETOMIUM GLOBOSUM
Authors: WALSH J. H. , HARLEY J. L. 
Published: May 2006

SummaryThe absorption of the sugars, glucose and fructose, by Chaetomium globosum does not involve an accumulation against an internal concentration but is associated with immediate assimilation. The process is sensitive to the presence of inhibitors, anaerobiosis, and to the concentration supplied. The relationship to concentration is hyperbolic and the half maximum rates occur at about 6–8 × 10‐3 M for fructose and 9 × 10‐5 M for glucose. Glucose and fructose compete for the uptake mechanism so that in mixed solutions when the glucose concentration is at about 13% of that of fructose the uptake of the latter is abolished.The uptake of carbohydrate from sucrose solutions is mainly an uptake of the hexose moeities released from sucrose. The amount of sucrose absorbed intact is very small. Sucrose is split by an enzyme system which appears to be located at or near the hyphal surface. It is relatively resistant to temperature and metabolic inhibitors and appears to be stimulated by alkali metal ions in solution.
PLANT GROWTH AND THE AERIAL ENVIRONMENT
Authors: EVANS G. C. , HUGHES A. P. 
Published: May 2006

SummaryIf it cannot be assumed that the rate of increase of dry weight of a plant per unit leaf area (unit leaf rate or net assimilation rate) is constant, the computation of a mean value for this rate over a period between two harvests requires information or assumptions as to the relationship between dry weight (W) and leaf area (1). With sufficient information the problem can be solved graphically, but it is usual to assume either that W = a+bL or that W = a+bL2, where a and b are constants, leading to two well‐known formulae which suffice for many purposes. For more precise work, it is here shown that the solutions of a general case, W = a+bLn, where n is a third constant, are related to these formulae in a manner depending only upon n and upon p, the ratio of leaf areas at the first and second harvest. Various methods of computing the constants are described, their significance is discussed, and it is shown that for the young stages of certain plants n is close to I and the constant a is negligibly small. Later n increases, and the constant a becomes significant. Finally these methods are used to recompute the estimates of unit leaf rate given in Paper II of this series.
MOVEMENT OF GROWTH REGULATORS IN PLANTS
Authors: McCREADY C. C. 
Published: May 2006

SummaryThe synthetic auxin 2,4‐dichlorophenoxyacetic acid (2,4‐D), labelled with carbon‐14 in the carboxyl group, was applied in blocks of agar gel to either the apical or the basal ends of segments cut from the petioles of young primary leaves of Phaseolus vulgaris, and the carbon‐14 appearing in receiving blocks at the other end was measured. When application was made to the apical ends, all the carbon‐14 accumulating in the receiving blocks appeared to be still in the form of 2,4‐D. This basipetal transport had a velocity of 0.6–1.0 mm/hour, and continued even when the concentration of 2,4‐D in the receiving blocks had become higher than that remaining in the donor blocks. Acropetal movement was much smaller. The ratio of acropetal to basipetal movement was approximately constant with time at low concentrations of 2,4‐D. At a high concentration, the ratio was increased; with longer segments it was decreased. More 2,4‐D entered the segments from blocks applied to the apical than to the basal ends. It is concluded that 2,4‐D is moved through these petiole segments by active polar transport.
A NUMERICAL REPRESENTATION FOR TAXONOMIC KEYS
Authors: OSBORNE D. V. 
Published: May 2006

SummarySome of the limitations of the usual type of dichotomous taxonomic key are pointed out. It is suggested that a particular method of representing the characteristic features of a species in numerical form can overcome some of these limitations. Identification by this method is rapid, can often be made correctly in spite of minor errois of observation, and requires no computation or computing equipment. The method may therefore be of particular use in the field.
THE DEVELOPMENT OF HALIDRYS SILIOUOSA (L.) LYNGB.
Authors: MOSS BETTY , LACEY ALAN 
Published: May 2006

SummaryFrom culture experiments it has been shown that the early stages in the development of Halidrys siliquosa are more similar to those of Cystoseira and Sargassum than to those of Fucus. The young plant has cryptoblasts along the primary frond and these are absent from the adult thallus. These hair pits are associated with the development of apical cells and the definitive axis of the adult thallus. The first year's growth is entirely vegetative and results in a pinnately branched thallus of ‘leafy laterals’only.Air vesicles are differentiated during the second year's growth and fertile receptacles are formed later. The receptacles are initiated from the end of August and new ones continue to be formed until December. Gametes are differentiated shortly before their discharge from December till March. After gamete discharge the receptacles disintegrate.The adult thallus shows a seasonal periodicity in growth and reproduction. There is a period of rapid vegetative growth during the spring and early summer which is followed by receptacle differentiation and‐then gamete discharge from December to March.
WOOD FIBRES WITH LIVING PROTOPLASTS
Authors: FAHN A. , LESHEM B. 
Published: May 2006

SummaryIt has been observed that in many woody plants the libriform fibres, and in some the fibre tracheids, retain living protoplasts in the entire sapwood. It is suggested, therefore, that the definition of fibres usually given in botanical textbooks, should be changed. From the preliminary study it appears that living protoplasts persist mainly in shrubs and subshrubs. As these life‐forms generally represent the woody vegetation of unfavourable habitats, it may be possible that living fibres are adaptive characters.
SOME ASPECTS OF THE THEORY OF DICHOTOMOUS KEYS
Authors: OSBORNE DONALD V. 
Published: May 2006

SummaryThe structure of dichotomous keys is discussed, and some general theorems are proved concerning the number and arrangement of the taxa in any given key. The possibility is considered that the various questions in a key may occasionally be answered wrongly, the key then leading to a wrong determination. It is shown that if this possibility exists, then the probability of a right determination is almost always improved by changing the structure of the key to make it as ‘short’as possible.The possibility is also considered of adding alternative identification paths through the key (‘reticulations’), starting at points where a particularly difficult question is asked. It is shown that this practice usually improves the key in respect of the determination of certain taxa, but may often diminish the overall probability of correct determination averaged over all taxa.
OBSERVATIONS ON NATURAL CLONES OF TRIFOLIUM REPENS L.
Authors: HARBERD D. J. 
Published: May 2006

SummaryAn attempt was made to map the distributions of some of the individual clones of Trifolium repens in an area of about 600 sq. yd of fixed dune vegetation. The field observations were checked in culture by morphological examination and by cross‐pollination. Most of the clones were limited to small patches of land (up to 6 yd across) and in relation to the vigorous vegetative spread of the species this might indicate a maximum age of genotype of about 20 years. However, one clone was found to be distributed in five discrete patches, each of small size but collectively giving a discontinuous spread of more than 20 yd. The five patches were limited to a narrow ecological zone suggesting specialization in ecological tolerance. The presence of a second genotype which occurred in two patches ecologically similar to one another but contrasting strongly with those of the first genotype indicated differentiation of ecological tolerance between genotypes within the population. These results are contrasted with those published earlier for Festuca. It is pointed out that if vegetative spread is limited by ecological factors the size of the area occupied by a clone cannot be regarded as a function of age, and that consequently the Trifolium genotypes observed might be just as ancient as those of Festuca.
THE PARASITISM OF CUSCUTA
Authors: MACLEOD D. G. 
Published: May 2006

SummaryThe presence of several transaminase enzymes has been demonstrated in Cuscuta reflexa and C. campestris. The activity of glutamate–aspartate transaminase in Cuscuta and host plants was measured. At least part of the transaminase activity of C, campestris and C. reflexa is located on the mitochondria. The presence of glutamic dehydrogenase in C. reflexa was demonstrated. An evolutionary scheme is postulated for the parasitism of Cuscuta.