An improved method for reconstructing a soil profile from analyses of a small number of samples

Most soil properties vary down a soil profile. In nearly every case a graph of the value of the property against depth (the ‘true’ curve) is smooth. However, a soil sample is usually taken from the whole of a horizon so that its analysis is the mean value for the horizon, and a graph of analyses against horizon depth is a ‘stepped’ profile. It is possible to produce a smooth profile by attributing each analysis to the mid-depth of its horizon and fitting a polynomial or spline curve through these values, but the former may produce erratic results, and both of them produce curves in which the true maxima and minima may be considerably damped. This paper explores the possibility of deriving a better reconstruction of the true profile from the same number of analyses by:

• (a) taking the samples for analysis from narrow layers at depths that appear to correspond to maxima, minima, or points of inflexion on the true curve, and fitting spline curves through their values;
• (b) fitting a modified ‘equal-area’ spline curve to conventional whole-horizon samples.

The latter is considerably superior and, in most cases, achieves a surprisingly close reconstruction of the true profile from which the samples were taken.     

Microbiology and histopathology of 'saddleback' disease of underyearling Atlantic salmon, Salmo salar L.

Abstract. Heavy mortalities of underyearling Atlantic salmon parr have occurred at the Mactaquac Fish Culture Station in New Brunswick as the result of 'saddleback' disease. The organism causing this lesion was isolated and identified as Flexibacter columnaris. This bacterium was transmitted to other salmon parr, where it produced the typical saddle lesion from which it was re-isolated. The condition was more readily transmitted at 20°C than at 15°C. Transmission required entrance to the dermis through a break in the epidermal surface and was unsuccessful in intact fish. The morphology of the saddleback isolate and its histopathological effect on the fish tissues is described. F. columnaris appeared to be restricted to the dermis and underlying muscle of the saddle area when histological techniques were used, although it was also isolated from the kidneys of some affected fish. The gills, kidney and other organs of the fish did not seem to be affected by the presence of F. columnaris.     

Seasonal changes in the germination responses of buried Lamium amplexicaule seeds

Spring-produced seeds of Lamium amplexicaule L. were buried in pots of soil in an unheated glasshouse in June 1978, and at 1–2-month intervals, for 27 months, they were exhumed and tested for germination in light and darkness at temperatures simulating those in the habitat from early spring to late autumn. Freshly-matured seeds were dormant, but by autumn 85% or more germinated in light at 15/6, 20/10, 25/15 and 30/15°C but only 7% or less in darkness. During late autumn and winter germination in light decreased at 25/15 and 30/15 °C but not at 15/6 and 20/10 °C, and germination in darkness increased at 15/6 and 20/10 °C. During late winter and early spring germination in light at 15/6 and 20/10 °C decreased, and seeds lost the ability to germinate in darkness. By the second autumn of burial, seeds germinated to near 100% in light at 15/6 to 30/15 °C and to 10–25% in darkness at 15/6 and 20/10 °C. The cycle of germination responses was repeated during the second winter and spring and the third summer of burial. Autumn-produced seeds were dormant when buried in November 1979, but by spring they germinated to 81 and 36% at 15/6 and 20/10 °C, respectively, in light. These seeds afterripened further during summer. The consequence of seasonal changes in germination responses is that (1) seeds can germinate in the habitat in late summer, autumn and spring but not in early- to mid-summer or in late autumn and winter and (2) during both germination seasons, seeds produced during the previous spring(s) and/or autumn(s) can germinate.     

Effect of organic vehicles on the pharmacokinetics of aminophylline administered intravenously to goats

Aminophylline dissolved in water, propylene glycol, or dimethyl sulfoxide was administered intravenously to goats in a randomized cross-over experiment. Model-dependent and model-independent pharmacokinetic parameters for theophylline were compared on the basis of the solvent used in the dosage form administered. No difference was found in any pharmacokinetic parameter. Thus, we found no evidence for the possibility that the organic solvents studied would confound pharmacokinetic investigations of theophylline and similar lipophilic drugs.