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  • 19th century physiology  (1)
  • Augmented nitrification assay  (1)
  • Springer  (2)
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  • Springer  (2)
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  • 1
    Electronic Resource
    Electronic Resource
    Application of an augmented nitrification assay to elucidate the effects of a spring barley crop and manures on temporal variations in rates (1997)
    Springer
    Biology and fertility of soils 24 (1997), S. 378-383 
    Details
    ISSN: 1432-0789
    Keywords: Key words Nitrification ; Manures ; Organic farming ; Controlling factors ; Augmented nitrification assay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of crop plants and farmyard or poultry manure applications on temporal variations in nitrification rates were measured in a field experiment. In order to elucidate factors which may have been governing such rates, an augmented nitrification assay was applied. The basis of the assay was to measure nitrification rates under circumstances where substrate, i.e. ammonium-ion, and water and spatial constraints had been removed. Nitrification rates showed marked temporal variation, of over one order of magnitude, throughout the growing season. Nitrification rates were also similarly increased when substrate and spatial constraints were removed, but distinct temporal variations still persisted. The pattern of such variations varied according to assay conditions in the augmented nitrification assay. Barley plants had a statistically significant effect on nitrification rates, positive early in the growing season and negative at the end. Manures stimulated nitrification, with poultry manure having a greater effect than farmyard manure, and there was evidence for a relationship between heterotrophic and autotrophic activity. Factors other than ammonium-ion concentration and water or spatial restrictions must also regulate nitrification rates in mineral soils; these could include population size or interactions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050261
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  • 2
    Electronic Resource
    Electronic Resource
    Diffusion Theory in Biology: A Relic of Mechanistic Materialism (2000)
    Springer
    Journal of the history of biology 33 (2000), S. 71-111 
    Details
    ISSN: 1573-0387
    Keywords: diffusion theory ; Fick ; 19th century physiology ; mechanistic materialism ; oxygen secretion ; metabolic organization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , History
    Notes: Abstract Diffusion theory explains in physical terms how materials move through a medium, e.g. water or a biological fluid. There are strong and widely acknowledged grounds for doubting the applicability of this theory in biology, although it continues to be accepted almost uncritically and taught as a basis of both biology and medicine. Our principal aim is to explore how this situation arose and has been allowed to continue seemingly unchallenged for more than 150 years. The main shortcomings of diffusion theory will be briefly reviewed to show that the entrenchment of this theory in the corpus of biological knowledge needs to be explained, especially as there are equally valid historical grounds for presuming that bulk fluid movement powered by the energy of cell metabolism plays a prominent note in the transport of molecules in the living body. First, the theory's evolution, notably from its origins in connection with the mechanistic materialist philosophy of mid nineteenth century physiology, is discussed. Following this, the entrenchment of the theory in twentieth century biology is analyzed in relation to three situations: the mechanism of oxygen transport between air and mammalian tissues; the structure and function of cell membranes; and the nature of the intermediary metabolism, with its implicit presumptions about the intracellular organization and the movement of molecules within it. In our final section, we consider several historically based alternatives to diffusion theory, all of which have their precursors in nineteenth and twentieth century philosophy of science.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004745516972
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