bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE BIRD FAUNA OF THE GALAPAGOS ISLANDS IN RELATION TO SPECIES FORMATION
Authors: SWARTH HARRY S. 
Published: January 2008

Summary.The Galapagos Islands possess a peculiar and highly characteristic fauna and flora. The abundant bird and reptile populations are nearly all of endemic species; of the land birds only two species occur elsewhere than in these islands. Studies bearing upon the origin of the Galapagos fauna have led to diverse conclusions; scrutiny of modes of variation has revealed some curious situations. The Galapagos have been variously regarded as the surviving remnants of a land‐mass, now sunken, that was formerly connected with the American mainland, and as oceanic islands that have appeared above the ocean as the result of volcanic upheaval. Study of the birds is confirmatory of the latter view. The avifauna is clearly not derived from the South American mainland directly to the eastward. Of the marine species there are one or two of southern origin, borne northward on the cold Humboldt current, and there are others which constitute local forms of species that are of world‐wide distribution. There is an important element definitely recognisable as of West Indian derivation, and others may have originated from the same source. There are a few species that clearly are not of West Indian ancestry, and there are a number that are too widely differentiated for recognition of their immediate affinities. The hypothesis is advanced that the inception of the Galapagos avifauna took place in a period when North and South America were separated by the sea; the relationship of the faunas of the West Indies and the Galapagos is to be regarded in the same light as relationships from one to another of the West Indian islands. The bird population of the Galapagos, abundant as regards individuals, is, as regards representation of different groups, of the sparse and miscellaneous character to be expected of chance‐controlled wanderers to distant islands.Conditions are uniform enough throughout the archipelago, so that, with much local variation, each island contains a fair representation of the same general assemblage of species. Trends of variation are seen in arrested stages of plumage in certain species, in a possible tendency to melanism in others. There are many variants of these situations. The outstanding group of birds is the endemic family, the Geospizidae, including 37 species and sub‐species out of the entire list of 89 breeding birds. Extensive variation and complicated relationships within this family are such as can probably not be duplicated in any mainland stock of birds. The observed variation presents difficulties to classification, and certain trends of development seem to act independently of natural selection. The Geospizidae afford a fine example of diversification unhindered by competition.
THE PROTEOLYTIC ENZYMES OF MICRO‐ORGANISMS
Authors: HAINES R. B. 
Published: January 2008

Résumé.The formation of exo‐enzymes may be shown in the case of bacteria by centrifuging off the organisms, with or without filtration, through a suitable filter candle or Seitz asbestos filter, and incubating with the appropriate substrate at the required pH. Further concentration and purification may be carried out by evaporation in vacuo at low temperatures (Hladik, 1910), fractional precipitation with ammonium sulphate (London and Pakhotina, 1917), precipitation, dialysis and re‐precipitation with alcohol (Munter, 1910), adsorption on alumina or kaolin and fractional elution with suitable buffers of selected pH (Willstätter, 1928; Hopkins, 1930), dialysis (Harden and Young, 1906; Walter, 1917), and extracting with glycerine (Macfadyen, 1892).With moulds and actinomycetes the mycelium may be filtered off through paper and suitable methods of concentration applied to the filtrate. For the preparation of endo‐enzymes of bacteria, autolysis may be used, alternative freezing and thawing (Young, 1929), grinding in an agate mortar (Stevens and West, 1922, a, b), or lysis with bile (Avery and Cullen, 1923). For yeasts and fungi the “acetone‐dauerhefe” process employed by Dox (1913), combined grinding and extraction of juice by high pressure (Buchner, 1898), and low temperatures (Rowland, 1910), are available, after which further precipitation may be carried out. Halderer (1909, 1910, 1912) investigated the conditions influencing filtration of enzymes through porcelain filters. Two interesting recent methods of following protein hydrolysis are by Krebs (1930) and Gates (1930). The former dissolved the protein in bicarbonate solution in the cup of a Warburg manometer in the presence of 5 per cent. carbon dioxide. As hydrolysis proceeds the carbon dioxide tension changes and may be read off on the manometer. Gates measured the reduction in density of exposed photographic film in a photometer, progressive proteolysis of the gelatin leading to release of silver. Viscometric methods are well adapted to the study of breakdown of gelatin (von Gröer, 1912; Haines, 1933). A nephelometric method of following proteolysis has been developed by Rona and Kleinmann (1928). Foreman and Graham‐Smith (1928) worked out titration methods for following the changes in meat broth during growth of Staphylococcus aureus.
THE EVAPORATION OF WATER FROM INSECTS
Authors: MELLANBY KENNETH 
Published: January 2008

Summary.This article deals with the way in which climatic conditions and insect metabolism affect the rate at which water is evaporated from insects' bodies.It appears that practically all the water evaporated from insects is lost from the tracheal system. At high temperatures the body wall of the cockroach becomes permeable to water.Experimental results may be explained by assuming that when the spiracles are closed, the air in the tracheae is saturated, and in most cases it remains saturated when the spiracles are opened. In some cases, however, particularly in very dry air, the air in the tracheae becomes somewhat dry. The evidence for these suppositions is mainly indirect, but appears reasonably conclusive.The proportion of dry matter in insects, and the ratio of bound water to free, cannot, of themselves, affect the resistance of insects to desiccation. The best protection against desiccation appears to be an efficient mechanism for closing the spiracles, together with the ability to conserve water in the rectum and pass dry excreta.Experiments in which the rate of loss of water is measured in air of various humidities show that the rate is more nearly proportional to the saturation deficiency of the air than to any other measure of humidity. As the temperature rises, the rate of loss at one saturation deficiency sometimes increases, because the insect opens its spiracles more frequently.Experiments to determine the conditions of temperature and humidity which limit survival and breeding of various species support the view that the rate of loss of water is proportional to saturation deficiency. In work of this kind, it is important that results be attributed to the effects of humidity only when humidity alone is the causal factor.The occurrence of optimum temperatures, at which insects can develop over a wider range of humidity than at higher or lower temperatures, is discussed, and a simple explanation is suggested.The ways in which the various environmental and internal factors influence the rate of loss of water are discussed, and the law governing the rate of evaporation of water from insects is stated in a revised form, and its implications are defined.
PRODUCTION OF LIFE IN THE SEA
Authors: HARVEY H. W. 
Published: January 2008

Summary.This review deals with the production of plants in the sea, which is controlled by a mosaic of factors, many of which are interrelated. Observations are collected and discussed, which relate to (i) the compounds of nitrogen and phosphorus directly utilized by the phytoplankton, and their rate of supply to the photosynthetic zone; (ii) the depth of this zone, which is determined by the quantity of light energy entering the water daily and the transparency of the water; (iii) the influence of temperature, of light, and of the concentration of nutrient salts, upon the growth rate of some diatoms; (iv) the dual effect of turbulence which, on the one hand, carries nutrient salts from below into the photosynthetic zone and, on the other hand, carries plant organisms to depths below the zone and, in some areas, increases the turbidity of the water thereby reducing the depth of the photosynthetic zone; (v) grazing by herbivores which deplete the breeding stock of plants but also excrete nutrient salts directly into the photosynthetic zone; (vi) the regeneration of nutrient salts by bacteria and enzymes; (vii) the supply of iron and other trace elements, of which manganese and divalent sulphur compounds are needed by some species of diatoms,The supply of such minor constituents is thought to play a considerable role in the distribution of plant life in the southern South Atlantic, where there is a high concentration of nutrient salts in the waters throughout the year and great differences in the density of the flora between different areas.Estimates of the magnitude of the annual production of plants below a square metre, arrived at by various indirect methods, are compared.Fluctuations in the annual plant production from year to year in the English Channel, assessed from the quantities of phosphate present in the water during the winter, show a marked correlation with the density of the fauna.Recent attempts to estimate the standing crop of phytoplankton in terms of food for animals are described, and tentative estimates of the carbon and phosphorus content of the standing crop below a square metre, when at its maximum in several seas, are compared.
CAMBRO‐ORDOVICIAN CEPHALOPODS
Authors: Miller A. K. 
Published: January 2008

Summary Volborthella and Salterella of the Lower Cambrian arc probably pteropods, rather than cephalopods. The oldest undoubted cephalopods are two species of Plectronoceras from the Upper Cambrian of eastern Asia; both are small curved brevicones with ellipochoanitic siphuncles. The oldest American cephalopods are from the uppermost Cambrian of the Ozark region, and they are referable to Shelbyoceras, which in general physiognomy resembles Plectronoceras. The nautiloids appear to have reached a climax during the earliest Ordovician times and again near the close of the Lower Ordovician; the second climax is characterized particularly by the appearance of nautilicones. The majority of Cambro‐Ordovician cephalopods are brevicones, but longicones are fairly abundant, and locally (in the Lower Ordovician) nautilicones are not particularly rare. Evolute specimens with closely spaced adoral septa and modified apertures are mature, rather than senile. Many Cambro‐Ordovician cephalopods have orthochoanitic siphuncles, others holochoanitic. In the adapical portions of the siphuncle of certain Early Palaeozoic holochoanites (both brevicones and longicones) there are numerous closely spaced endocones, which are believed to have developed from diaphragms. The siphuncle of one genus of Lower Ordovician orthochoanites contains a central tube of unknown function. In another Lower Ordovician genus the walls of the siphuncular segments are solid‐V‐shaped in longitudinal section. The adapical portions of at least some of the early nautilicones show a siphonal caecum much like that of modern Nautilus, an orthochoanitic siphuncle, a small umbilical perforation, and a nepionic line near the end of the first volution. Both cameral and siphuncular deposits occur in Lower Ordovician nautilicones. Presumably brevicones gave rise to longicones and these in turn to gyroceracones and nautilicones. During the Lower Ordovician, holochoanites developed from ortho‐choanites; and cyrtochoanites, which in America at least are not known to exist before the Middle Ordovician, also evolved from orthochoanites.
THE INVESTIGATION OF PLANT NUTRITION BY ARTIFICIAL CULTURE METHODS
Authors: ARNON D. I. , HOAGLAND D. R. 
Published: January 2008

SummaryThis review presents a general survey of artificial culture methods employed in the investigation of plant nutrition. Several types are described, including liquid‐culture methods and those which depend on a solid inert medium. The advantages of artificial culture procedures for growing plants are pointed out, as one means of studying soil‐plant interrelations, as well as various questions in plant physiology and plant biochemistry. These methods have been indispensable in the study of the chemical elements essential to the growth of higher plants, especially of those elements needed in minute quantities. The techniques of artificial culture are also of great value for the investigation of the absorption of ions by roots. These techniques serve likewise for inquiries into the interreactions of climatic conditions and mineral nutrients. Among other topics considered are the application of artificial culture methods to researches on the functions in plant metabolism of inorganic nutrients, the role of colloids in absorption of ions, horticultural and agronomical problems, and commercial production of crops.
THE STRUCTURE and PERMEABILITY OF BLOOD CAPILLARIES
Authors: DANIELLI J. F. , STOCK A. 
Published: January 2008

Summary(1) Outside the single layer of endothelial cells composing the basic unit of the vertebrate blood capillary is a perithelium of connective tissue fibres, associated with which are connective tissue cells, contractile (Rouget) cells, etc. (2) Constriction of the lumen of a capillary may occur (a) by the intrusion of a few endothelial cells into the lumen, (6) by a more general activity of a length of endothelium, or (c) by the action of extra capillary cells, in which case folding of the capillary may ensue. (3) The rate of nitration through the capillary walls is controlled by (a) mechanical factors, (6) plasma and hormone factors, (c) local tonus and nervous control, (d) dietary factors. (4) The conclusion that there is a gradient of permeability to certain dyes is due to a misunderstanding of the experimental observations: the distribution of dye in such cases is precisely that predictable by Starling's ultrafiltration hypothesis for the case of a capillary slightly permeable to colloid. (5) Poiseuille's equation applies fairly accurately to the flow in blood capillaries, and the rate of development of oedema in perfused preparations obeys an equation based on Starling's hypothesis and on Poiseuille's equation. (6) Most substances reach the tissue cells as a result of filtration through the pores in the intracellular cement. Only a few substances, such as oxygen, pass with readiness through the endothelial cells themselves. (7) The capillary network may undergo changes which, with a given systemic blood flow, permit of independent variation (a) in the rate of blood flow through a tissue, (b) in the rate of filtration through the walls of the capillaries.
THE SHOOT APEX IN PTERIDOPHYTES
Authors: WARDLAW C. W. 
Published: January 2008

Summary(1) Some of the developments which have made for a fuller understanding of the shoot apex in pteridophytes are discussed, particular attention being paid to morphogenetic processes, (2) Of the several interpretations of growth and cellular arrangement at the apex which have been advanced, that of Naegeli, in which the importance of the apical cell is emphasized, appears to be most applicable to the livingpteridophytes; Sachs's geometrical‐mechanical views emphasize another aspect of organization at the shoot apex, while his comprehensive outlook on the nature of the meristematic region as a whole deserves careful attention. (3) In the pteridophytes, with some exceptions, there is no obligate relation between apical segmentation and organogenesis and histogenesis, i.e., segmentation does not determine organogeny. (4) The value of the facts of apical segmentation in phylogenetic studies is discussed. (5) The history of causal morphology is briefly outlined. If the phyletic history of plants were before us in full, the problems of causal morphology would still remain. These includethe external and internal factors which determine morphogenetic processes and specific structural organization. (6) The development of leaf primordia in ferns and in dicotyledons is compared: the data show that a knowledge of the fern leaf may be regarded as essential to any general theory of leaf development. Such a theory must include a consideration of spatial, metabolic and mechanical factors. (7) The view is developed that shoot buds in ferns occupy an interfoliar position at the time of their inception, the position which they eventually occupy on the shoot or leaf base being determined by the distribution of growth. Bud development thus requires a study of the integrated growth activities at the apex. (8) An account is given of the initial and subsequent differentiation and development of vascular tissue at the shoot apex; spatial, metabolic and mechanical factors which may be implicated are discussed. The view‐is held that the structural arrangements observed should be interpreted in terms of growth and not of adult functional activities. (9) Views based on comparative studies which relate to the fundamental nature of the shoot are of two kinds, i.e. axial and phytonic, a constructional unit being taken for granted‐in each case. It is anticipated that investigations of the growing point from the standpoint'of causality may eventually lead to new concepts regarding the shoot type of organization. An indication is given of some of the factors which may lend themselves to further investigation.
THE ONTOGENY OF THE SHOOT APEX IN DICOTYLEDONS
Authors: PHILIPSON W. R. 
Published: January 2008

SummaryWork on the early appearance of the shoot apex in the embryo has been carried out along two lines. First, by formal descriptions of early segmentation, and, secondly, by the recognition of zones within the embryo which foreshadow the tissue systems of the seedling. The latter is the more fruitful approach when problems of wide morphological interest are being investigated. A study of this kind has suggested, for example, that the shoot is homologous with the stele of the root, the outer tissues of the root having no counterpart in the shoot.The tunica‐corpus concept can now be accepted only with considerable reservations. The depth of the tunica may fluctuate during development, and the tissues derived from an apical layer may vary quite capriciously. Nevertheless, stratification of the apex is considered a characteristic feature of angiosperm shoot apices. Complementary to this stratification is a zonation within the apical meristem corresponding to that of gymno‐sperms. That is to say, the central cells of the apical meristem are larger with less dense protoplasm than the surrounding peripheral cells. The term initiating cell is proposed for this stage in cellular development.The initiation of leaves and the delimitation of provascular meristem below the apex are briefly described, and the bearing of these facts on the relationship between stem and leaf is discussed. The shoot is regarded as a unit, and it is concluded that the angiosperm leaf may be regarded more properly as an outgrowth of the stem than as a modified branch system.Some recent work on phyllotaxis is discussed, it being shown that an experiment designed to demonstrate that the position of leaf primordia is independent of the pattern of vascular tissue below them is inadequate for this purpose. An interesting theory of phyllotaxis recently propounded by Plantefol fits many facts of apical development.Little is known of developmental changes during vegetative growth. Those which precede flowering are better known, and seem to be explicable in terms of a redistribution of growth. These changes in the position, rate and direction of cell divisions bring about changes in the organization of the apical meristem in reproductive apices. With the cessation of growth in length, the central zone is replaced by cells of the same nature as those of the peripheral zone, which then extends uniformly over the apex. Gregoire's view of the irreducibility of the reproductive and vegetative apices is examined. Most of his evidence has proved ill‐founded, but a difference in organization remains. This change in organization is regarded as one of a series which occur in the development of the shoot; only with the accomplishment of all stages in its development is a shoot complete.
THE REPTILIAN CEREBRAL HEMISPHERES
Authors: GOLDBY F. , GAMBLE H. J. 
Published: January 2008

Summary1. The reptilian hemisphere has been studied mainly from a morphological point of view and for the most part with techniques which are capable of providing no more than a preliminary survey of the distribution of the perikarya of neurones and of the topography of the main fibre systems.2. The hemisphere is small, and almost completely smooth. Its most characteristic feature is a strio‐amygdaloid complex of great relative size, and in particular the differentiation of the dorsal part of the striatum.3. Olfactory structures are very well developed in Chelonia which in this respect resemble amphibians and primitive mammals. They are proportionately smaller in other reptilian orders, and some lizards are microsmatic. The pattern of the olfactory connexions resembles that of amphibians and mammals. A characteristic feature of many of the Squamata is a high degree of development of the accessory olfactory bulb and of the amygdaloid nucleus which receives fibres from it.4. A cortex showing some of the characteristics of the mammalian cerebral cortex is present in all reptiles, and hippocampal, dorsal and piriform areas are always recognizable. The dorsal area occupies a region where the mammalian neocortex must have been formed. A thickening in its anterolateral border (the ‘primordium neopallii’ of some authors) may represent a phylogenetic stage in the development of the mammalian neocortex. Equally valid arguments can be produced for regarding it as a reptilian specialization and for deriving the mammalian condition from the more generalized amphibian condition.5. Embryological investigations are purely descriptive and have shown little more than that the pattern of development of the reptilian hemisphere conforms in its general features to that of other tetrapod classes.6. Functional investigations indicate that the basal parts of the hemisphere may be of importance in effecting orientation between the animal and its environment, perhaps by facilitating neural mechanisms at lower levels and by integrating the elements of behaviour patterns. The results so far as the cortex is concerned are mainly negative; nothing comparable to the mammalian ‘motor area’ is present.7. The limitations of the techniques employed are discussed, and it is concluded that the main value of the information at present available is as a basis for systematic classification, and for application of experimental techniques necessary for the investigation of morphogenetic and functional problems.