bluuebunny/crossref_metadata_2025_split huggingface dataset:
RESPIRATORY EVAPORATION IN BIRDS
Authors: SALT GEORGE WILLIAM 
Published: January 2008

Summary1. Many birds are capable of varying the rate of evaporative heat loss during respiration as a means of temperature regulation.2. Respiratory heat loss becomes increasingly important as air temperatures rise. Above the body temperature of the bird it is the only means of heat loss.3. The rate of respiratory heat loss varies from one species of bird to another. The rate is also dependent on environmental atmospheric humidity.4. The rate of heat loss by respiratory evaporation is dependent on the difference in vapour pressure between that of the respiratory surface and of the inspired air, on the degree of saturation of the expired air, and on the volume of air expired per breath and per unit time.5. There is a constant relation between breathing rate and heat production in the House Sparrow above the upper critical temperature.6. Other things being equal, there is a constant relation between evaporative rate and the vapour pressure difference between the air and the evaporative surface, if one assumes that the vapour pressure of the respiratory surface is equal to that of water at the rectal temperature of the bird.7. When variations due to differences in respiration rate, metabolic rate, atmospheric humidity and body size are excluded, in some species of birds the rate of evaporative heat loss is essentially constant at air temperatures above the upper critical temperature (the upper limit of the thermo‐neutral zone, see p. 114, footnote). In other species the rate of respiratory evaporation increases as air temperatures rise above the upper critical temperature.8. From this evidence and other data in the literature, there appear to be four classes of species: one in which respiratory evaporation as a temperature‐regulating mechanism is unimportant or non‐existent; a second in which respiratory evaporation takes place in the lungs and air sacs and in which, at air temperatures above the upper critical temperature, increased evaporation is achieved only by an increased respiratory rate; a third in which respiratory evaporation takes place in the lungs and air sacs but the evaporative rate can be enhanced without an increase in respiratory rate; and a fourth in which evaporation takes place in the more anterior regions of the respiratory tract such as the trachea or buccal cavity.9. These four groups are interpreted as representing various stages between two extremes of specialization. One extreme is represented by species of cold arid regions in which all or most of the tidal air passes through the lung parenchyma. Respiratory evaporation and hence heat loss is thus minimized. The other extreme is represented by species of hot humid regions in which the major function of ventilation is to provide evaporative heat loss. Respiratory gas exchange is a minor purpose and only a small fraction of the tidal air traverses the lung passages.
A QUANTITATIVE BALANCE BETWEEN SUBSTRATES AND METABOLIC PRODUCTS OF THE MAMMARY GLAND
Authors: BARRY J. M. 
Published: January 2008

Summary1. An attempt has been made to assess from published experiments, and largely for the goat, the principal compounds that are absorbed from the blood by the lactating mammary gland, the quantities of each that are absorbed during the formation of 100 ml. of milk, and the proportion of each of the major components of milk, and of the carbon dioxide expired by the gland, which is derived from each of the components of blood.2. An assessment has first been made of which compounds of blood could, and which could not, be quantitatively significant metabolites of the gland. This has been done by calculating the maximum amount of each compound which would be available to the gland during the formation of 100 ml. of milk, from its concentration in blood together with the rate of blood flow through the gland.3. For components of blood which could be quantitatively significant metabolites of the gland, it should be possible to discover whether or not they are absorbed in significant amounts by making arterio‐venous measurements. Those measurements which have been made are considered, and rough calculations have been made of the quantity of each compound which is absorbed from the blood of the goat during the formation of 100 ml. of milk.4. From this information, and from the results of experiments with isotopic tracers, an attempt has then been made to assess the proportion of each of the major components of milk, and of the carbon dioxide expired by the lactating gland, which is derived from each of the components of blood.5. It is realized that the calculations made in this article are approximate. In conclusion, possible improvements in technique are briefly considered which would enable a balance of this kind to be made accurately.
THE ONTOGENY OF THE VASCULAR CAMBIUM IN THE STEM OF SEED PLANTS
Authors: PHILIPSON W. R. , WARD JOSEPHINE M. 
Published: January 2008

Summary1. A striking characteristic of the vascular cambium is its plasticity. It may arise in any position in any tissue except the epidermis. It may function in a variety of ways, giving rise to xylem or phloem alone, or to both tissues. If both xylem and phloem are formed from the same cambium, they may be derived from opposite faces of the meristem or be combined as bundles or be mixed less regularly. One cambium may be succeeded by another and the method of functioning of successive cambia may vary. A number of these possibilities may be combined in one plant either simultaneously or at different stages of growth.2. The mode of operation of the cambium in monocotyledons is so different from that of most dicotyledons, that it is unlikely that they can be homologous. It is probable that a cambium has been acquired independently in several lines of mono‐cotyledonous evolution, although the virtual identity of the cambium wherever it occurs in monocotyledons is remarkable. Some dicotyledonous cambia are almost equally distinctive. To distinguish these from the usual bi‐directional cambium, the term uni‐directional cambium is applied to them in this account. A uni‐directional cambium may be a primitive feature of the families Chenopodiaceae, Amarantaceae, and Nyctaginaceae, but essentially identical cambia have been acquired in the Styli‐diaceae, the Phytolaccaceae and in several independent lines within the Compositae.3. Another feature of the cambium is the pressure of competition between its cells. This is especially evident during the early growth of a stem, when increase of circumference is relatively great. Many cells are produced by pseudo‐transverse divisions within the initial layer. These cells increase in size by intrusive growth, and many are lost. Survival has been shown to be influenced by a wide variety of factors.4. A large number of investigations has established a pattern of variation in size of xylem elements within the tree. This reflects a similar pattern of size variation in the cambium. In broad outline this pattern is found in most trees which have been investigated, although considerably modified in timbers derived from storeyed cambia. Groups of woody plants showing other modifications of the pattern have been described.5. The transformation of fusiform initials into ray initials and vice versa is another example of the plasticity of the cambium. The maintenance of the proportion of ray to fusiform initials characteristic of a species indicates that cambial activity is a well‐co‐ordinated and orderly process. The importance of a correct proportion of ray tissue among the longitudinal elements of the xylem is evident.
GLYCOPROTEINS IN MEMBRANES
Authors: COOK G. M. W. 
Published: January 2008

Summary1. Although the classical models of biomembranes have emphasized the lipid and protein nature of these structures, a small quantity of carbohydrate is present as glycoprotein and glycolipid in animal cell membranes. In this article an attempt has been made to indicate that such carbohydrate materials should be considered in any complete model of animal cell membranes.2. Various techniques that have demonstrated the presence of glycoproteins in animal cell membranes have been discussed here. In particular, cell electrophoresis, especially when the measurements are combined with specific enzyme treatments of the cells, has indicated that the net negative surface charge on intact viable cells is mainly due to sialic acid‐containing glycoproteins and not as previously thought to ionizable phosphate groups associated with a complex phospholipid system.3. Membrane‐bound antigens are complex carbohydrate‐containing macro‐molecules whose antigenic activity is principally associated with the configuration at terminal positions on the carbohydrate chains. Enzymic degradation of the glycoproteins of the intact plasma membrane of cells, especially erythrocytes, causes profound changes in the immunological behaviour of the cell.4. Histology and electron microscopy have indicated the presence of carbohydrate at the periphery of many mammalian cells. Some workers consider that such materials are present in a ‘cell coat’ covering the plasma membrane, rather than in the membrane itself.5. Studies on the isolation and characterization of membrane glycoproteins have indicated that small oligosaccharide units linked to O‐seryl or glutamyl residues in proteins are important structural units in plasma membranes.6. The glycosylation of proteins takes place within the membranes of the endo‐plasmic reticulum. Studies of glycoprotein biosynthesis suggest that the cell is able to synthesize a diversity of cell‐surface structures from a relatively small number of monosaccharides.7. Modification of the sialic acid‐containing glycoproteins of the plasma membrane affects the transport of materials in and out of cells. Glycoproteins are present in membranes other than the plasma membrane, and are therefore considered to be integral components of membranes; hence the designation ‘cell coat’, whilst useful as a descriptive term, should not be taken to indicate that glycoproteins are constituents of a functional entity separate from that of the membrane.8. Evidence that membrane glycoproteins may act as sites of interaction between cells is discussed. The involvement of glycoproteins in such a role would explain why the cell had developed a biosynthetic process capable of producing varied surface oligosaccharide structures from monosaccharides.
THE SUBLETHAL EFFECTS OF SYNTHETIC INSECTICIDES ON INSECTS
Authors: MORIARTY F. 
Published: January 2008

Summary

The synthetic insecticides have been used in steadily increasing quantities since the Second World War and are non‐specific poisons, and so pose the possibility of sublethal effects on wild populations of animals.
The organochlorine insecticides in general, and some of the cyclodienes in particular, are usually much more persistent than the organophosphorus and carbamate insecticides, both in the environment and within individual insects.
Analyses of samples suggest that traces of the organochlorines are widely dispersed over the entire globe.
Although the evidence is incomplete, all of these synthetic insecticides appear to exert their primary toxic lesion by interference with the conduction of impulses in the nervous system.
The complete pattern of events that ends in death includes the release of secondary toxins into the blood. These are probably physiologically active compounds, normally present, but liberated in excessive amounts by excessive nervous stimulation.
A condition similar to the late, paralytic, stage of insecticidal poisoning can also be produced, in Periplaneta americana, by excessive physical stimulation and there are similarities in the physiological changes caused by both types of stimuli. This suggests that a generalized stress syndrome develops after excessive nervous stimulation. However, this similarity has so far only been demonstrated for this one insect species.
Sublethal effects have so far only been looked for cursorily. Interpretation of sublethal effects is sometimes difficult; apparent differences between dosed and control individuals may sometimes be caused by selective mortality of the dosed individuals. Four main types of effect have been found.
Latent toxicity, which is evident as a reduction of longevity or of death at particular developmental stages, has been found only with organochlorines, appears to be linked with fat metabolism, and shows clearly that sublethal effects may be produced a long time after acquiring a dose of a persistent insecticide.
All types of synthetic insecticide can affect reproductive potential, and may increase or decrease the number of eggs produced. Egg fertility or development of offspring may also be affected. Reductions are sometimes caused directly by inhibition or distortion of ovary development, sometimes indirectly by reduced feeding.
The few studies on behaviour have shown that activity may increase, feeding decrease, and the acceptance threshold of sucrose be lowered.
DDT induces the formation of more detoxifying microsomal enzyme in Triatoma infestans.
I suggest that latent toxicity and some behavioural changes are probably caused by direct effects on the nervous system, but that some of the other results may be secondary effects associated with the stress syndrome. There is also the possibility of direct insecticidal action on other systems.

It is a pleasure to thank our librarian, Mrs Jean King, for her unfailing help in tracing references.
A SURVEY OF NEUROENDOCRINE PHENOMENA IN NON‐ARTHROPOD INVERTEBRATES
Authors: GOLDING D. W. 
Published: January 2008

SUMMARY

Neurosecretory phenomena are apparently ubiquitous among Metazoa.
In Hydra, neurosecretory products are probably involved in the control of growth and reproduction.
Secretory elements in the central nervous system of turbellarians probably promote fission, regeneration and reproduction.
The cerebral ganglia of nemertines are the source of a hormone which exercises an inhibitory influence on maturation of the gonads and the development of somatic sexual characteristics. A principle secreted by the ganglia and/or the associated cerebral organs controls weight regulation. A sex hormone controls sexual differentiation.
Secretory neurons may influence the production of exsheathing fluid and ecdysis in nematodes.
In nereid polychaetes, a single hormone which originates from the cerebral neuroendocrine system apparently promotes segment proliferation and inhibits maturation. However, in certain other polychaetes, contrasting endocrine mechanisms seem to operate.
In lumbricid oligochaetes, a hormone secreted by the cerebral ganglion (and possibly by other nervous centres also) promotes gonadal activity and the differentiation of somatic sexual characters. In some species the ganglion exerts an inhibitory influence on the associated processes of ‘diapause’ and posterior regeneration. The cerebral and suboesophageal ganglia are implicated in the control of osmoregulation. Cerebral neurosecretory cells in limicolous oligochaetes may influence regenerative growth and osmoregulation.
The cerebral ganglia of leeches secrete a gonadotrophic hormone.
In gastropod molluscs, hormones secreted by the cerebral ganglia, glandular ‘dorsal bodies’ and/or optic tentacles are responsible for the control of the development of the reproductive tract, and the activity of the gonads. Contrasting mechanisms are thought to operate in the different gastropod groups and there is conflicting evidence particularly with respect to the endocrine functions of the optic tentacles and the gonads. The ‘bag cells’ of the abdominal ganglion of ApZysiu secrete a hormone which induces egg‐laying. Cells in the pleural and parietal ganglia probably control osmoregulation in Lymnaea.
The optic glands of cephalopods secrete a gonadotrophic hormone, but sex hormones are apparently absent. The functional significance of the neurovenous tissues (presumptive neurosecretory complexes of unusual character) is obscure in most cases.
The radial nerves of starfish are the source of a hormone which induces the production of I‐methyl adenine by the follicle cells of the gonad. This second principle stimulates oocyte maturation and the shedding of male and female gametes.
The relevance of such information to the development of certain biological concepts and to various aspects of comparative physiology is briefly discussed.
CONVERSION EFFICIENCIES IN HETEROTROPHIC ORGANISMS
Authors: CALOW P. 
Published: January 2008

Summary1. The maximum possible efficiency at which living systems are able to convert input nutrients to their own biomass is between 70 and 80 %.2. Conversion efficiency in bacteria, protozoa and metazoan cells in culture approximates more closely to 60%.3. Conversion efficiency during embryonic development begins below 60% and rises above this level in the later stages.4. Very young, post‐natal organisms have high net efficiencies; 50 to 70% in homeotherms and 50 to 80 % in poikilotherms.5. In cellular systems, capable of proliferation, conversion efficiency is independent of food supply. This means that conversion is directly dependent on nutrient supply.6. Control of growth at the tissue level may occur through the control of the supply of nutrients to the tissues and its entry into the cells.7. Compensatory growth, after and during undernutrition, involves increased absorption efficiency and reduced metabolic costs.
PRODUCTION AND ROLE OF INTERFERON IN PHYSIOLOGICAL CONDITIONS
Authors: BOCCI VELIO 
Published: January 2008

Summary1. There is convincing evidence that a number of agents such as bacteria, viruses, endotoxins, foreign proteins, smokes and chemicals come into contact under physiological conditions with the lymphoid tissue associated with the gut and/or bronchial systems. Endogenous lectins and proteases may also act as mitogens on the central and peripheral immune system.2. It is suggested that these agents act as inducers of interferon (and some also as immunogens), so that local production of interferon is turned on successively from cell to cell depending upon their responsiveness and upon the periodic inflow of inducers.3. On the basis of a number of different features, it is proposed to distinguish between an ‘acute’ and a ‘physiological’ interferon response. In the latter, the interferon‐producing cell influences the neighbouring cells by short‐range humoral transmission (paracrine control) and possibly by cellular interaction, while the route of the general circulation is preferentially used in the former response.4. It is suggested that the physiological interferon response, although previously overlooked, has great biological importance because production of interferon at strategic sites can maintain active defence systems essential for survival.5. It is to be expected that the physiological interferon response, although amenable to experimental verification, may be difficult to detect. On the basis that interferon is normally absent from serum, it is suggested that most of the released immune‐type interferon is either bound by cells surrounding the site of its synthesis or catabolized locally.6. It is postulated that the progressive decline of the physiological interferon response with increasing age may represent one of the factors favouring the insurgence of autoimmune diseases and tumours in the process of ageing. It is also suggested that the involution of the thymus may in part be due to intrathymic production of interferon induced by proteases released from macrophages.
PHYCOLOGY AND HEAVY‐METAL POLLUTION
Authors: RAI L. C. , GAUR J. P. , KUMAR H. D. 
Published: January 2008

Summary1. All heavy metals, including those that are essential micronutrients (e.g. copper, zinc, etc.), are toxic to algae at high concentrations.2. One characteristic feature of heavy‐metal toxicity is the poisoning and inactivation of enzyme systems. Many of the physiological and biochemical processes, viz., photosynthesis, respiration, protein synthesis and chlorophyll synthesis, etc., are severely affected at high metal concentrations.3. Some algae inhabit waters chronically polluted with heavy‐metal‐laden wastes from mining and smelting operations; Nodularia sp., Oscillatoria sp., Cladophora sp., Hormidium sp., Fucus sp. and Laminaria sp., etc., occur in metal‐rich waters. These algal forms are probably more capable of combating the toxic levels of heavy metals and this attribute is a result of physiological and/or genetic adaptations. The sensitivity or tolerance to heavy metals varies amongst different algae. The phenomena of multiple tolerance and co‐tolerance may be exhibited by some algae.4. Heavy‐metal pollution causes reduction in species diversity leading to the dominance of a few tolerant algal forms. The primary productivity also decreases after metal supplementation.5. The uptake and accumulation of heavy metals can be active (energy‐dependent), passive (energy‐independent), or both.6. Heavy metals can be safely stored as intranuclear complexes by some algae. Notwithstanding this, some changes in the cell wall can enable the algae to tolerate heavy metals by checking the entry of the metals (exclusion mechanism).7. The metal content of algae growing in a waterbody may yield valuable information for simulating heavy metal pollution: several species of Cladophora and Fucus have been extensively used for this purpose.8. Several factors affect and determine toxicity of heavy metals to algae. At low pH, the availability of heavy metals to algae is greatly increased, as a consequence of which pronounced toxicity is evident. Hard waters decrease metal toxicity. Some ions, e.g., calcium, magnesium and phosphorus, can alleviate toxicity of metals.9. The presence of other metals can influence toxicity of a heavy metal through simple additive effect or by synergistic and antagonistic interactions. Similarly, other pollutants can influence heavy‐metal toxicity.10. The toxicity of heavy metals depends upon their chemical speciation. Various ionic forms of a metal characterized by different valency states, may be differentially toxic to a test alga.11. Amino acids, organic matter, humic acids, fulvic acid, EDTA, NTA, etc. can complex with heavy metals and render them unavailable. This may eventually lead to less toxicity.12. Heavy‐metal toxicity largely depends upon algal population density: the denser the population the more numerous the cellular sites available, leading to decreased toxicity.