bluuebunny/crossref_metadata_2025 huggingface dataset:
The London Business School with Gower Publishing
Authors: Currie David , Dicks Geoffrey
Published: January 2008

The Government has recognised that the balance of risks has shifted in the last six months. Even though the pound has been devalued by around 15 per cent and suspended from the ERM, the probability of a significant pick‐up in inflation over the next 12 months is low: the more serious risk is that the recession, which showed signs of deepening in the third quarter, turns into a slump. It is for this reason that the Autumn Statement announced measures, both monetary and fiscal, to increase demand and more particularly to try to rebuild confidence which has taken a battering over more than two years of recession, most notably in the housing market, where in the immediate aftermath of the ERM diédâle prices continued their sharp fall. On the fiscal side the measures were constrained by a seriously adverse trend in the PSBR, with some imaginative use of ‘time‐limited’ measures which will boost demand in the short run without adding to government borrowing in the medium term. On the monetary side the Chancellor sanctioned the third 1 percent reduction in interest rates since the pound has been in free float. He was responding partly to criticism that the earlier two cuts had achieved rather little, though Mi. Lamont might have been advised that steering the economy by monetary policy is akin to steering an oil tanker: it takes a considerable time to respond. The danger, especially if rates come down to 6 per cent before the end of the year or even, as some are urging, to Sper cent, is that rates will have to rise sharply again before the end of next year to head off a renewed bout of inflation. This may seem a remote possibility at the present time but, as Milton Friedman taught us long ago, the lags in monetary policy are long and variable: it is nonsense to imagine that the cuts in rates that we have seen in the last two months could have yet had any impact on the economy. The worry is that, with the pound I5 per cent down on ERM levels, they will have an adverse effect on inflation in, 1994‐5.
Manufacturing Industry and the Balance of Payments Adjustment: The United Kingdom Case
Authors: BALL JAMES , ROBERTSON DONALD
Published: January 2008

The thesis of this essay is that it is unlikely that economic growth in the UK during the rest of the 1990s will be balance‐of‐payments constrained in any significant sense. Our conclusion is that manufacturing industry does not and will not play a unique role in Britain's economic future. These propositions are not to be confused with two distinct and related ones. The first is that the fact that the balance of payments need not be seen as a constraint does not rule out the possibility of other problems associated with the balance of payments such as we have seen in the recent past. Secondly, the fact that manufacturing industry is not in any sense a unique part of economic activity in no way lessens its importance as a major and significant sector. This paper is in no sense a critique of manufacturing industry.
The Competitiveness of UK Manufacturing: Performance and Prospects
Authors: PREVEZER MARTHA , SMALL IAN , TEMPLE PAUL
Published: January 2008

The competitiveness of UK manufacturing and its future prospects are examined in terms of productivity, the performance of high technology industries and the relationship between science and technology. Die main findings are that concentrating on productivity performance can be misleading and attention should also be paid to the structural aspects of competitiveness, especially the relationship between the science base arid industrial technology. On this basis we conclude that if the UK is to realise fully the competitive potential of technological change, differences in these structural aspects of competitiveness need to be addressed.
COUNTING THE COST OF HIGHER BASE RATES
Authors: Sentence Andrew
Published: January 2008

It is a brave Chancellor of the Exchequer who raises interest rates when inflation is at record low levels and there are few signs of overheating. But Kenneth Clarke is clearly trying to give substance to his commitment ‐ made in June's Mansion House Speech ‐ to pursue stable monetary and fiscal policies. In that speech, the Chancellor told his City audience that the government had “not created the conditions for the strongest recovery in Europe in order to throw it away by creating yet another boom followed by bust”.

There is widespread agreement with the Chancellor's objectives. But the difficult question for economic management is how high interest rates will need to go in order to contain inflation and keep the economy on course. In this Forecast Release, we examine this question as well as assessing the likely impact of the first rise in base rates for five years.
REAL EXCHANGE RATES WHAT CAN THEY TELL US?
Authors: Lade Jenni Greens
Published: January 2008

This is the first two articles which focus on the behaviour and determinants of real exchange rates. JenniGreenslade discusses the recent movements in real rates and the usefulness of ‘equilibrium’ exchange rates. The case of France is used as an example of an alternative approach which may be adopted, using time series methods which will be explored in the next article.
WHAT HAS BEEN HAPPENING TO EUROPEAN TRADE?
Authors: Chui Michael
Published: January 2008

This article by Michael Chui and John Whitley looks at trade behaviour within the European Union. They argue that measures of trade integration do not support the conventional view that intra‐EU trade has increased steadily over the past 20 years, although there may have been a sharp rise during the 1990s. They also find evidence from econometric analysis of a shift in export pricing behaviour during the 1980s. UK export performance after exit from ERM shows some distinct differences from the other economies who also devalued at the same time.
IS THE DOLLAR REALLY UNDER‐VALUED?
Authors: Greenslade Jenni
Published: January 2008

In the second of tow articles focusing on the determinants of real exchange rates Jenni Greenslade and John Whitely look at estimates of “equilibrium” exchange rates derived from the FEER approach. They find evidence that the dollar is currently under‐valued but its equilibrium level is expected to depreciate in the future. Estimates of equilibrium rates are shown to be sensitive to assumptions about trade elasticities and the opening up of the service sectors in international trade.
Structural change and economic behaviour: The case of UK exports
Authors: Hall Stephen
Published: January 2008

In this paper Stephen Hall, Giovanni Urga, and John Whitley apply a new econometric technique to date unknown breaks in UK export behaviour. They show how the evidence points to a structural shift in 1979. Although there is some support for a supply‐side interpretation in that there have been changes in the behaviour of prices, there has also been a shift in the underlying demand for UK exports. They also find that variables which proxy changes in the quality of UK exports, or other supply‐side influences, do not properly account for the observed structural break in UK export performance.
China's soft landing: Too good to be true?
Authors: Bai Hong , Sentance Andrew
Published: January 2008

Chinese inflation reached a peak of almost 30% in late 1994 but has since fallen back to below 10%. Growth has eased in response to weakening demand but the slowdown has been very modest, with growth of around 10% recorded to last year. In this article, Hong Bai and Andrew Sentance critically examine this apparent “soft landing” and suggest that the reduction in inflation may be more apparent than real.
Innovation, imitation and growth in a changing world economy
Authors: Sentance Andrew , Levine Paul
Published: January 2008

The rapid growth of East Asia, which has had such a dramatic impact on the world economy, is widely seen as a process of “catch‐up” in which poorer nations grow rapidly assimilating Western and Japanese “know‐how”. However, this pattern is now changing. In particular, Korea and Taiwan are becoming centres of innovative activity. In this article, Michael Chui, Paul Levine, Joe Pearlman and Andrew Sentance analyse these developments. They argue that evidence of increasing innovation outside the West will be beneficial to world growth over the longer term and should be welcomed, not regarded as a threat.
Is the financial system to blame for “low”UK investment?
Authors: Rose Harold
Published: January 2008

The sluggishness of capital spending over the recovery has reinvigorated the debate over UK investment performance. It has frequently been alleged that the UK financial system holds back investment, while the institutions of continental European countries – particularly Germany – are more supportive of long‐term spending by companies. In this article, Harold Rose examines the theoretical and factual basis for this line of argument. He warns policy‐makers against acting to promote investment on the basis of arguments which are either not securely founded or which are directly contradicted by the evidence.
THE DETERMINATION OF THE SALT ERROR OF INDICATORS AND THE ACCURATE ESTIMATION OF THE pH OF SOLUTIONS BY COLORIMETRIC METHODS
Authors: SAUNDERS J. T.
Published: January 2008

1. It is shown that, using the sulphonphthalein indicators recommended by Clark and Lubs, it is possible to detect differences in pH of no more than 0·02.

2. A curve is deduced by means of which it is possible to determine the salt error of Cresol Red for any difference of concentration between the buffer mixture and the solution of unknown pH.

3. A simple method of determining the salt error of any other indicator by comparison with Cresol Red is outlined.
THE MEASUREMENT OF THE CARBON DIOXIDE OUTPUT OF FRESH WATER ANIMALS BY MEANS OF INDICATORS
Authors: SAUNDERS J. T.
Published: January 2008

Tables are given showing the relationship of the pH of a dilute solution of carbonates to the total CO2 content. Animals are placed in such dilute solutions which are coloured with indicators, contact with the atmosphere is prevented by a layer of oil and the pH as measured by the changing tint of the indicator records also the output of CO2. An output of CO2 of no more than 7middot;0001 c.c. is easily and accurately measured.
THE SPAWNING OF ECHINOIDS
Authors: FOX. H. MUNRO
Published: January 2008

(1) The extrusion of the genital products of echinoids is due to the contraction of muscle fibres in the gonad walls, more abundant in the ovary than in the testis. The contraction of these muscles can be artificially stimulated.

(2) A spawning male stimulates ripe individuals of both sexes which are in the neighbourhood to spawn. A spawning female stimulates ripe males to spawn.

(3) After spawning Strongylocentrotus lividus re‐forms ripe eggs in nine days at a temperature of 17–19°.
A MATHEMATICAL THEORY OF NATURAL AND ARTIFICIAL SELECTION. PART II THE INFLUENCE OF PARTIAL SELF‐FERTILISATION, INBREEDING, ASSORTATIVE MATING, AND SELECTIVE FERTILISATION ON THE COMPOSITION OF MENDELIAN POPULATIONS, AND ON NATURAL SELECTION.
Authors: HALDANE J. B. S.
Published: January 2008

Expressions (2·1), (3·1), (4·1), (5·1) are found for the composition of Mendelian populations subjected to partial self‐fertilisation, inbreeding, assortative mating, or selective fertilisation, and equations (2·2), (3·2), (4·2), (5·2) derived for the effect of selection on such populations. The effect of selection is greatly increased by inbreeding and self‐fertilisation.
THE MECHANISM OF CELL‐DIVISION I. THE FORCES WHICH CONTROL THE FORM AND CLEAVAGE OF THE EGGS OF ECHINUS ESCULENTUS
Authors: GRAY J.
Published: January 2008

1. Soon after fertilisation the protoplasm at the surface of the egg of Echinus esculentus is differentiated off from the internal phase of the egg. The egg is thus divisible into two phases, the ectoplasm and the endoplasm.

2. Except during the process of cleavage fine processes of endoplasm extend out into the ectoplasm.

3. The outer surface of the ectoplasm is of a solid extensible nature. It is not markedly elastic. The underlying portion of the ectoplasm is fluid.

4. When cleavage occurs the ectoplasm tends to collect in the segmentation furrow and eventually divides the two portions of endoplasm from each other.

5. The normal form of the fully divided cell is due to the pressure exerted on the endoplasm by the ectoplasm.

6. The ectoplasm is only stable in the presence of calcium and potassium. It has different osmotic properties to those of the endoplasm. It rapidly shrinks in dilute acids.

7. During cleavage the normal form of the cleavage furrow is due to the force exerted by the ectoplasm against the force exerted by the asters.

8. The form and extent of the cleavage furrow depend on the position and size of the asters. The asters are capable of deformation by the ectoplasmic pressure.

9. Evidence is presented to show that the growth of the two asters must lead to a redistribution of the different phases of the protoplasm (peripheral endoplasm, and ectoplasm), such as is actually observed. Further, the final result of the enlargement of the asters must lead mechanically to normal cleavage. There are, thus, two essentials for cleavage, (i) the cell must be differentiated into two immiscible layers, ectoplasm and endoplasm, (ii) the cell must contain sufficiently large asters to bring about a redistribution of the endoplasm round these two centres.

10. The variations in the types of cleavage characteristic of other animal cells can be brought about in Echinoderm eggs by varying either the extent of the force exerted by the ectoplasm, or by varying the size or position of the two asters.

11. Cell‐division in Echinoderm eggs is the direct result of the asters reaching a critical size.

In conclusion, I wish to express my gratitude to Mr R. Elmhurst, Director of the Marine Station, Millport, N.B., for providing me with facilities at Millport, and for his unfailing assistance in maintaining a constant supply of material during the period 1921‐24.
SPERMATOGENESIS OF LITHOBIUS FORFICATUS
Authors: NATH VISHWA
Published: January 2008

1. The spermatogonium is a somewhat spindle‐shaped cell with granular mitochondria and a few curved Golgi rods.

2. During the growth phase a spermatogonium enlarges into a giant egg‐like spermatocyte.

3. Each spermatocyte contains granular mitochondria, a large number of highly curved Golgi elements and curious cytoplasmic fibres which at times attain huge dimensions. Each Golgi rod may have a distinct archoplasmic sphere associated with it.

4. In a centrifuged spermatocyte the cytoplasmic fibres are thrown at one end but the mitochondria and the Golgi elements remain uniformly scattered.

5. The cytoplasmic fibres are well preserved with Mann‐Kopsch and chromeosmium. They are destroyed to a large extent by fixatives containing acetic acid. Hence all the earlier workers do not figure them.

6. The “metaplasm” and the “formations ergastoplasmiques” of Blackman and Bouin brothers respectively are really the Golgi elements which are not completely destroyed by acetic acid.

7. During meiosis the mitochondria and the Golgi elements are distributed into two sub‐equal parts.

8. When the spermatid is formed most of the Golgi rods assume the form of rings.

9. All the mitochondria and the Golgi elements go into the tail of the sperm and directly form the tail sheath.

10. The acrosome is probably secreted by a few Golgi rings which get stuck to the anterior face of the nuclear membrane of the maturing sperm. It is very prominent in the ripe sperm.

11. A few small granules constantly occur on that portion of the nuclear membrane of the maturing sperm from which the axial filament starts. They are intensely blackened with omit acid and are very probably of the Golgi origin.
THE PROBLEM OF GRAFT HYBRIDS AND CHIMAERAS
Authors: WEISS. F. E.
Published: January 2008

In the introductory paragraphs of this review, the question was discussed whether after grafting, any effect of scion on stock or vice versa was known to occur. It was indicated that apart from the infectious chlorosis, a supposed virus disease, any influence of stock on scion or scion on stock is generally regarded as nonexistent. Professor Daniel, however, who has had unrivalled experience of grafting, holds the opposite view and believes strongly in the intermingling of characters of stock and scion (hybridation asexuelle) caused particularly by his method of mixed grafting.

The earliest graft hybrid which has been scientifically investigated, the so‐called “Bizzarria” Orange, is then described. It is regarded by some as a true graft hybrid, by others as a synthetic chimaera of periclinal constitution. Other instances of sectorially diverse oranges may be due to partial segregation of heterozygous forms of Citrus.

The well‐known and much discussed Cytisus Adami seems according to the investigations of Buder (1910 and 1911) to be what Baur (1910) has called a periclinal chimaera with a core of the Common Laburnum surrounded by an epidermal layer of Cytisus purpureus.

Though according to Baur (1919) and Meyer (1915) the Crataegomespili are also periclinal chimaeras with a core of the hawthorn surrounded by one or more layers of the medlar, the more recent investigations of Haberlandt (1926) and Weiss (1925) as well as previous observations by Daniel (1914) throw some doubt on the chimaeric structure of these so‐called graft hybrids.

The constitution of Pirocydonia is still uncertain and the Amygdalopersica described by Daniel (1914) seems likely to be a heterozygous plant.

Of the various forms of growth obtained by Winkler by grafting tomato on nightshade stock and vice versa, four seem to be definitely proved to be periclinal chimaeras, but the constitution of Solanum Darwinìanum is still doubtful, and it may possibly be a true graft hybrid formed by a union of vegetative cells.

The formation of chimaeric growths of variegated plants both of sectorial and periclinal constitution was experimentally established by Baur (1909) for Pelargonium and further investigated by Bateson (1919 and 1920), Chittenden (1925) and others. This has led to interesting discussions and observations concerning the part played by the plastids in the reproductive processes of plants and generally in the inheritance of variegated leaves.

A further point of interest is the suggestion made by Chittenden (1930) that certain eversporting forms of flowers may be of chimaerical constitution.
THE RESPIRATION OF INSECTS
Authors: WIGGLESWORTH V. B.
Published: January 2008

The review covers the ground of external and internal respiration in insects, but deals neither with quantitative changes in metabolism, nor with the intimate processes of oxidation in the tissues.

The general anatomy and histology of the tracheal system are described. The form of the tracheae and their mode of ending in the tissues is extremely varied in different insects and in different organs. The question whether the tracheal endings contain fluid or air and the problem of what forces keep the larger branches filled with gas are discussed in detail. The embryological development of the tracheal system and the nature of the “spiral thread” are briefly considered.

The exchange of gases in the tracheal system is effected primarily by diffusion. This is modified by opening and closure of the spiracles (“ diffusion control ”) and by mechanical ventilation of the larger tracheal branches (“ventilation control ”). The mechanism of tracheal ventilation is discussed at length: including the part played by the air sacs and the question whether there is a directed stream of air through the tracheal system.

The respiratory movements are controlled by nerve centres, variously situated in different insects; and these centres may be stimulated either by oxygen want or by carbon dioxide excess.

The relative importance of the spiracles and the skin in respiration, especially in the elimination of carbon dioxide, is discussed.

Under the respiration of aquatic insects the functions of the “blood gills,”“tracheal gills ” and “ cuticular gills ” are reviewed, and the problems connected with the “ hydrofuge ” structures of aquatic insects and the air stores which they carry are considered. The respiration of parasitic insects presents many parallels with that of aquatic forms.

The part played by the blood of insects as a carrier of oxygen is discussed in detail.
THE DERMATOPHYTES
Authors: GREGORY. P. H.
Published: January 2008

The dermatophytes are a group of fungi which parasitise animals by invading the keratinised portions of the epidermis. They appear to be unable to attack internal organs and are apparently dermatotropic. Ringworm in its various forms is a primary localised dermatophyte infection.

The concept of the activity of the dermatophytes has been enlarged by the recognition that they can also determine secondary non‐parasitic skin lesions on distant parts of the body. Several records of isolations of these fungi from the blood indicate that spores may be carried from the primary lesion to other parts of the body by means of the blood stream.

Hairs infected by certain species of dermatophytes show a green fluorescence in ultra‐violet light not possessed by uninfected hairs. This phenomenon can be utilised to detect infected hairs among normal ones. The fluorescence is due to a water‐soluble substance which can be extracted from infected hairs.

The wealth of spores and other organs produced in cultures on certain animal and vegetable media suggests that these fungi have a natural saprophytic stage in their life history. It is also possible that the saprophytic stage occurs on naturally infected hairs after they fall from the animal body.

The dermatophytes in culture are subject to variation. The particular irreversible degenerative mutation known as “pleomorphism” can take place in isolates derived from either a single aleuriospore or a single fuseau. Pleomorphism appears to be due to a toxic action on the organism of monosaccharides and disaccharides. In media containing polysaccharides pleomorphism is not observed.

Asci have been reported by several workers. While certain of these records appear to be unsubstantiated, others point to an affinity between the dermatophytes and the Gymnoascaceae. The classification of the 200 or more species is in a state of chaos. The newer systems show few advantages over Sabouraud's revised classification.
THE RETENTION AND PHYSIOLOGICAL ROLE OF UREA IN THE ELASMOBRANCHII
Authors: SMITH. HOMER W.
Published: January 2008

The high urea content (2·0 and 2·5 per cent.) that characterises the blood, body fluids and tissues of the Elasmobranchii owes its origin to the relative impermeability of the gills and integument to this substance, and to the circumstance that the urea is actively conserved by the elasmobranch kidney.

In consequence of this physiological uraemia, the elasmobranch is osmotically superior to its environment, even in sea water, and is able to absorb at least a minimum quantity of water for the formation of a urine that is isotonic or hypotonic to the blood, in accordance with the osmotic limitations of the fish kidney.

We may suppose that the uraemic state tends to develop and to be regulated more or less automatically; urea is constantly being formed by the ordinary metabolic combustion of protein; water shortage leads to oliguria and urea retention, and the accumulated urea in the blood raises the osmotic pressure of the latter to a point where water is again available by direct absorption. Water plethora (as in fresh water) leads to diuresis and increased urea excretion, which in turn lowers the osmotic pressure of the blood and in some measure, at least, reduces the rate of water absorption.

Trimethylamine oxide, which imparts about one‐quarter as much osmotic pressure to the blood as does urea, is also conserved by the elasmobranch; the fact that this substance is present in the urine in lower concentration than in the blood suggests that, like urea, it is actively reabsorbed from the glomerular filtrate.

This physiological uraemia is apparently an archaic biochemical habit acquired early in elasmobranch evolution, since it is shared by the divergent orders of the subclass. Presumably it is a secondary mode of osmotic regulation superimposed upon the more primitive one of branchial regulation, as observed in the teleostomes.

The cleidoic egg, unique (among the fishes) in the Elasmobranchii, and the viviparous mode of reproduction, are viewed as adaptations to urea retention, protecting the embryo against the loss of urea during its early development.

Urea retention enables the Elasmobranchii to maintain a considerably greater rate of urine formation (water excretion) than is observed in the marine teleosts, a fact that perhaps explains why the former do not show the glomerular degeneration or the aglomerular development observed in the latter.

Whereas urine formation in the marine teleosts appears to be carried on normally at a reduced level considerably below the maximum possible rate, the elasmobranchs appear to maintain a maximal (though small) degree of glomerular activity at all times. Unlike the teleosts, they appear to possess no mechanisms for reducing glomerular activity; it may be that because of their superior osmotic position, due in turn to their physiological uraemia, they have never been faced with the necessity for conserving water to an excessive degree in the kidneys, and have therefore never evolved the means for doing so.
GENETICS IN ITS APPLICATION TO PLANT BREEDING
Authors: HUDSON P. S.
Published: January 2008

The importance of Mendelism in relation to practical breeding problems is illustrated by reference to early work on the inheritance of economic characters.

Examples are given of improved varieties that have been produced by individual plant selection. The possibilities of success are shown to be dictated by the completeness of the material and one of the essentials for successful breeding is shown to be the collection of adequate and representative stocks of initial breeding material. This is illustrated largely by reference to Russian work, which has also elucidated the laws governing the distribution of plant varieties, characters and genes.

The possibilities of putting interspecific or distant crosses to practical use are analysed and cases where this has been done are cited. Chromosome duplication is shown to be a frequent phenomenon in such cases and to be a factor greatly increasing the economic value of such distant crosses. Numerous cases are quoted and the phenomenon is shown to have played an important role in the origin of new species and forms in nature. Its experimental control is thus of great practical value.

The origin of new forms of pathogenic fungi by hybridization and mutation is illustrated and shown to be a serious obstacle in breeding for disease resistance.

Examples are given where the obstacle has been overcome by breeding methods and other cases are mentioned where the problem of disease resistance remains unsolved.

The role of mutations in the origin of new forms of agricultural plants is discussed and the possibilities of effecting this process artificially are analysed.

The phenomenon of vernalization is described, with special reference to breeding. The significance of this and other recent physiological studies in producing forms possessed of earlier maturity is discussed.

The nature of plant yield is discussed and reference is made to attempts to analyse and regulate this by genetical methods.
BIOCHEMISTRY OF THE LOWER FUNGI
Authors: BIRKINSHAW J. H.
Published: January 2008

The study of the biochemistry of the lower fungi received a great impetus from the classical researches of Wehmer begun in 1891. The more recent developments are here reviewed. The biochemical characteristics of moulds often correspond closely with the taxonomic features and thus assist in classification.

A medium suitable for mould growth must contain the elements sulphur, phosphorus, potassium, and (probably) magnesium. Traces of certain heavy metals, namely iron, zinc, copper, and manganese, seem to be essential for the growth of Aspergillus mger and probably of other moulds.

Combined nitrogen is also essential for growth and may be supplied in inorganic or organic form.

The possible sources of carbon are very diverse, alcohols, carbohydrates and many organic acids being readily utilized.

Although moulds are essentially aerobes, some species can tolerate a low oxygen tension. Diminution in the oxygen supply may alter considerably the products of metabolism.

Small amounts of certain organic substances specifically stimulate or inhibit some of the metabolic processes of moulds. Vitamins of the B group have a favourable effect on growth and sporulation in the case of some species. Certain moulds are able to elaborate substances inhibitory to other micro‐organisms.

The metabolic products are very varied in nature and range from the simpler plant acids (oxalic, fumaric, malic and citric acids), polyhydric alcohols and products of alcoholic fermentation to substances containing non‐benzenoid rings such as derivatives of furane, pyrone, tetronic acid and cyclopentanone, substances containing benzenoid rings, such as derivatives of benzene, benzoquinone, anthraquinone and xanthone, pigments, sterols, fats, phospholipins and complex polysaccharides. Vitamins of the B group and the provitamins A and D are also found amongst mould products. In presence of arsenic, certain species such as Scopulariopsis brevicaulis produce volatile organic arsenical compounds. Substances containing chlorine as part of the organic molecule are also synthesized from inorganic chlorides, and organic nitrogenous compounds including proteins from inorganic nitrogen. Evidence is thus afforded for the outstanding synthetic activities of the lower fungi.

Whilst the mechanism of synthesis is as yet an unsolved problem, the suggestion is advanced that some of the complex products may arise from the polysaccharides which are of such frequent occurrence in mould metabolism.
PROPERTIES OF THE CELL SURFACE
Authors: HARVEY E. NEWTON , DANIELLI J. F.
Published: January 2008

Measurements of the tension at the cell surface show that the tension lies between 1·0 and 0·1 dyne. The results of measurement of the tension at simple oil‐water interfaces are discussed in relation to this and it is shown that a simple lipoid layer is not sufficient to explain the low tension at the cell surface; the low tension must be brought about by the adsorption of protein upon the lipoid surfaces. This gives rise to a picture of the cell surface which involves, as a minimum, a bimolecular layer of lipoid molecules between two layers of protein molecules. Measurements of the thickness of the plasma membrane, of its permeability and wetting properties, are found to be compatible with this model. The acidic groups of the protein and lipoid can react with cations to give a sodium‐calcium antagonism. The membrane permits preferential penetration of lipoids, and at the same time offers a physical basis for pore and mosaic effects. High temperature coefficients of penetration are found to be explicable by a simple physical mechanism. It is shown that by variation of the pH of the external medium it is possible to distinguish between three possible mechanisms for ionic penetration; in the case of the erythrocyte the mechanism appears to be simple diffusion through a lipoid layer. The wetting properties of the plasma membrane also indicate that it is fatty in character, and that, in the case of Arbacia eggs, the pellicle is liquid.

It is concluded that the structure of the plasma membrane must be similar to that suggested as a minimum possible structure.
THE FINE STRUCTURE OF BIOLOGICAL SYSTEMS
Authors: PICKEN L. E. R.
Published: January 2008

1. Present‐day interest in the study of fine structure may be traced back to the work of the botanist, Carl Nägeli, to whom the conception of the micell is due.

2. The continuation of Nageli's optical studies of biological structures, the development of X‐ray analysis, and the investigation of the properties of long chain high polymers, have led to the extension and modification of Nägeli's ideas.

3. Two main types of molecular aggregate are of particular importance in biological systems—linear (or fibrous) and laminar structures. These may be classified as subcellular, extracellular and supracellular.

4. The subcellular structures which have been examined include: protein fibres from the sap of virus‐infected plants; chromosomes; asters and spindles; and contractile fibrils (muscle fibrils, myonemes, pseudopodia and cilia). These all appear to be composed of chain molecules arranged approximately parallel to the long axis of the structure in question.

Laminar subcellular structures include the surface membranes of animal cells (nerve fibres, echinoderm eggs, red blood corpuscles) and the outer portion of the rods and cones of vertebrate retinae. These are composed apparently of alternating layers of protein and lipoid molecules.

5. Extracellular fibrous structures are represented by elastoidin, collagen, elastin and chitin; laminar structures by the keratinous egg cases of selachians, the cellulose test of tunicates and chitinous integuments in general. The relation of these to other natural and synthetic high polymers is discussed.

6. The category of supracellular Structures, that is, of macroscopic fibrous or laminar structures of multicellular origin includes (a) hair and muscles, and (b) enamel and bone.

7. It is clear that a close parallel in structure and behaviour exists between biological materials and high polymer substances. The morphological implications of this parallel are discussed and the importance of molecular morphology for the biologist is considered.
THE GENETICS AND CHEMISTRY OF FLOWER COLOUR VARIATION
Authors: LAWRENCE W. J. C. , PRICE J. R.
Published: January 2008

1. The principal flower colouring matters are the anthocyanins, anthoxanthins and carotinoids. Variation in colour depends upon the presence or absence of one or more of these substances, upon structural alterations in their molecules, changes in thep pH of the cell sap, or quantitative changes affecting the amounts of pigment produced.

2. Pigment production is genetically controlled, and in a number of cases complementary genes are involved.

3. Variation in the amount of any pigment is also gene controlled. Such quantitative differences can be interpreted in terms of the velocity of the reactions involved in pigment production.

4. Modifications of the chemical structure of anthocyanins, including the state of oxidation, glycosidal type and probably the degree of methylation are each determined by simple gene relationships. In certain cases reactions are incomplete, giving rise to mixtures of anthocyanins.

5. The synthesis of anthocyanins in the plant is correlated with that of anthoxanthins. Some workers consider that the anthocyanins are formed from flavones or flavonols, but the most comprehensive theory, put forward by Robinson, postulates parallel formation of anthocyanin and anthoxanthin from the same intermediate. On this theory cyanidin and quercetin are synthetically the simplest members of their classes, others requiring additional stages of oxidation or reduction. The above view is supported by statistical analysis of the distribution of anthocyanins in flowers, fruits and leaves.

6. Heritable chemical differences result in the first place from gene action. They may be accentuated or minimized by gene interaction, which can modify dominance relationships and is sometimes the causal factor of epistasy. A study of gene interaction can also help in the determination of the sequence of gene action.
THE CRITERIA OF PURITY USED IN THE STUDY OF LARGE MOLECULES OF BIOLOGICAL ORIGIN
Authors: PIRIE N. W.
Published: January 2008

The limits, in weight and chemical stability, of the group of substances referred to as large molecules are discussed and the range is arbitrarily taken as from particles unresolvable by the microscope to those with molecular weight 5000. A unit of molecular weight is proposed and its advantages are discussed in cases where the nature of the bonds holding a particle together is uncertain.

Four distinct meanings that can be carried by the word pure are described, and examples are given of each type of purity.

The types of observation generally made and presented as evidence that a substance is pure are considered under seven headings. Chemical analysis and crystallinity are the least reliable, and specific serological tests can only show the absence of contaminants whose presence is suspected. The measurement of end‐points, whether by serum precipitation or infection, is subject to several errors and can at best only indicate whether or not the major constituent of a preparation may be serologically active or infective.

Electrophoresis, ultracentrifugation and studies based on the principles of the Phase Rule, i.e. solubility and partition measurements, give the most reliable evidence of purity at present available. Several reasons are given for thinking that even these methods may be fallible.
THE FUNCTION OF PHOSPHATE IN CELLULAR ASSIMILATIONS
Authors: M. KALCKAR H.
Published: January 2008

Two different types of carbonyl oxidation exist:

(I) Carbonyl + HaO + pyridine‐enzyme

← carboxylate + reduced pyridine‐enzyme.

This type of oxidation is practically irreversible and consequently liberates a large amount of free energy. The normal redoxpotential of this system is extraordinarily low, i.e. carbonyl is a very strong reducing agent.

(2) Carbonyl + phosphate + pyridine‐enzyme

← carboxylphosphate + reduced pyridine‐enzyme.

This type of oxidation is reversible and the change in free energy accordingly very small, which means that the normal redoxpotential of the system: carbonyl + phosphate ← carboxylphosphate + 2←+ 2H+ is very close to that of the system: pyridine‐enzyme ← reduced pyridine‐enzyme + 2←+ H+.

Thus replacement of water by phosphate in the carbonyl oxidation eliminates a great fall in free energy by transforming the labile carbonyl into an equally labile acid anhydride, carboxylphosphate.

The degradation of the polyalcohol structure of the sugar acid (glyceric acid) to the α‐keto acid structure of pyruvic acid releases a considerable amount of energy.

Moreover, in this case the energy is directed and preserved by means of a phosphorylation.

I am indebted to Dr D. M. Needham (Cambridge) for her generous help in preparing the manuscript for publication and to Prof. C. F. Cori, Dr G. T. Cori and Mr S. P. Colowick for their valuable and helpful suggestions.
THE EVOLUTION OF SEX IN FLOWERING PLANTS
Authors: LEWIS D.
Published: January 2008

1. The importance of combined genetic and systematic analysis of sex for its evolutionary interpretation has long been understood in animals. It now seems possible to make ah evolutionary interpretation of sex in plants by similar methods.

2. From the sporadic distribution of dioecious species throughout mainly hermaphrodite families of flowering plants, it is inferred that dioecious species have evolved from hermaphrodites.

3. From the more frequent association of dioecious species with monoecious species than with hermaphrodites, it is inferred that they have evolved more frequently by means of a monoecious intermediary.

4. Highly organized sex‐determining mechanisms of dioecious plants can evolve from single gene segregation, as shown (a) by the synthesis of dioecious strains of hermaphrodite species, and (b) by the analysis of sex in dioecious species of plants.

5. This evolution is illustrated by the study of sex chromosomes and shows the transition from the type where the two chromosomes are indistinguishable to highly complex systems. Lower stages are commonest in plants, higher stages in insects and mammals.

6. Male sterility which has become established in wild populations of hermaphrodite species is cytoplasmically inherited in all known cases. This system is not considered to be a transitional stage in the development of dioecy but rather as another stable outbreeding mechanism.

7. Sporadic distribution and lower differentiation of sex chromosomes agree in showing that sex differentiation is short‐lived in flowering plants. This is to be expected since sex separation in sessile organisms, in comparison with other outbreeding systems in plants, suffers from two shortcomings: (a) that the degree of outbreeding is inflexible, and (b) that utilization of gametes is wasteful. Male sterility is not subject to these limitations.

8. This gametic wastage is mitigated by changes in the sex ratio. Such changes are effected by the differential pollen tube growth of male and female determining pollen grains. For this reason it is the male that usually becomes the heterogametic sex.

9. We can thus have an intelligible evolutionary interpretation of sex in plants when we consider (a) the sporadic occurrence of sex separation, (b) the simplicity of the mechanism determining this separation, and (c) the great diversity of other sexual breeding systems.
EXTEROCEPTIVE FACTORS IN SEXUAL PERIODICITY
Authors: A. MARSHALL F. H.
Published: January 2008

1. In all mammals and probably in all vertebrates there is an internal endocrine sexual rhythm with alternating periods of rest and activity. This cycle is usually adjusted to external seasonal changes and with some marked exceptions spring is the period of greatest sexual activity, but there is much specific variation and among ruminating mammals breeding is generally in autumn.

2. Among tropical and subtropical animals breeding is not nearly so restricted to definite seasons, and there is evidence that ecological factors play a part in its recurrence.

3. In individual animals which are made to cross the equator there may be two seasons of sexual activity in the year and the times of breeding are eventually reversed though the original endocrine rhythm may be partly maintained for some time.

4. Experiments with light and ultra‐violet irradiations indicate that with the majority of vertebrates exteroceptive stimuli dependent upon these processes are of primary importance in adjusting the cycle to changing periodic environmental conditions.

5. The evidence shows that the factors in question act through the intermediation of the central nervous system and the anterior pituitary body.

6. The cycle is liable to considerable modification by exteroceptive stimuli arising from the relations between the sexes and between the mother and her offspring. Thus ovulation in various species of vertebrates may depend upon stimuli normally arising from the male but which may be imitated by experimental methods.

7. Sexual display and courtship phenomena among various classes of animals, while undoubtedly in some species serving to keep the pairs together and thus securing a ‘marriage bond’, have the further and much more general function of promoting an effective synchronization of the male and female sexual processes, thus favouring successful procreation.

8. The synchronization is mainly effected by pituitary stimulation which is often mutual, the stimuli acting through the intermediation of the hypothalamus, as in the case of other stimuli.

9. Whatever the exteroceptive stimulus the anterior pituitary is the regulator of the gonadal function.
BIOLOGICAL RACES IN PARASITIC PROTOZOA
Authors: HOARE CECIL A.
Published: January 2008

Biological races are defined as such subdivisions of a morphological species as are distinguishable by differences in biological characters only. Though biological races are well represented in diverse groups of parasitic Protozoa, their true nature is in most cases concealed under separate specific names.

In parasitic Protozoa biological races differ from each other in various aspects of their host‐parasite relations. These may be manifested in host‐restriction (or host‐specificity), as in trypanosomes of the brucei group, containing races confined to man and to other mammals; in intestinal amoebae and flagellates comprising human and batrachian races; and in human and simian malaria parasites (Plasmodium). Likewise, races parasitic in the same vertebrate host may be restricted to distinct vectors, as in piroplasms (Babesia) of cattle and dogs.

There are races which cause different diseases in the same host, usually with a distinct localization in its tissues, e.g. Leishmania in man and dogs, and trypanosomes of the evansi group, causing dourine and surra. Others again vary in the degree of virulence to the host, e.g. piroplasms of the genera Theileria and Babesia. A variation in pathogenicity to one or more hosts characterizes some geographical races of the same parasite, e.g. local strains of human Plasmodium, and of Trypanosoma evansi. Finally, in certain races various differential characters may be combined.

Variations in the host‐parasite relationship, as manifested by different races of Protozoa, are determined by the degree of their adaptation to the physical and chemical conditions in the host. These conditions include, among others, body temperature, quality of the digestive juices, nutrition (diet), and properties of the serum (parasiticidal action). The mutual adaptation of parasite and host involves reciprocal reactions, among which the serological reactions of the host are especially interesting, for they throw light on the intimate constitution of parasitic microorganisms. There is reason to believe that biological races of some parasitic Protozoa‐like the intraepecific ‘types’ of bacteria‐differ from each other in antigenic composition, while retaining common antigens characteristic of the species as a whole. Antigenic constitution is, therefore, correlated with the biological peculiarities of these races (at least in blood parasites), and since antigens consist of qualitatively different chemical substances, the distinction between biological races resolves itself into differences in the chemical structure of the antigenic components of the organisms in question. Biological races in parasitic Protozoa appear to be stable and hereditarily fixed. The biological criteria for their differentiation and the constancy of their diagnostic characters are advanced as arguments in support of an independent taxonomic status for biological races.