Later Stages Of Decay Research Articles

Transmission of Sacbrood Disease to Individual Honey Bee Larvae1

Sacbrood disease was transmitted experimentally to honey bee, Apis mellifera L. larvae of all ages from hatching to 4 days old by inoculating food in the larval cell with various filtrates of diseased larvae with a micrometer syringe. Up to 90% of the larvae died with symptoms typical of sacbrood. Microscopic examination of dead larvae confirmed the absence of bacteria. Four percent or less of control larvae treated with an equal volume of heat-sterilized filtrate or of water or left undisturbed developed sacbrood. Filtrates prepared from white (recently dead), brown (intermediate stage of decay), or black (late stage of decay) larvae which had died of sacbrood produced successively smaller percentages of infection. A severely infected comb placed in the brood nest of a normal colony did not spread the infection.

Wiener-Hermite Expansion in Model Turbulence in the Late Decay Stage

The Wiener-Hermite functional expansion, which is the expansion of a random function about a Gaussian function, is here substituted into the Burgers one-dimensional model equation of turbulence. The result is a hierarchy of equations which (along with initial conditions) determine the kernel functions which play the role of expansion coefficients in the series. Initial conditions are postulated, based on physical reasoning, criteria of simplicity, and the assumption that the series is to represent the late decay stage (in which the Gaussian correction is small and also decreasing with time). These are shown to justify an iterative solution to the equations. The first correction to the Gaussian approximation is calculated. This is then tested by evaluating the correction to the flatness factor, which for an exactly Gaussian function has the value 3, but which has been found by experiment (in real three-dimensional fluids, of course) to have a value which deviates from the Gaussian value increasingly rapidly with the order of the derivative. We utilize this effect as a test of the inherent ability of the Wiener-Hermite expansion to bring to realization the physical properties implicit in the Navier-Stokes or Burgers equations. The various contributions to the flatness-factor deviation, when computed, do show a potential capability of providing a theoretical basis for the effect.

Soil Oribatei. I. Feeding Specificity among Forest Soil Oribatei (Acarina)

Large numbers of living soil mites were obtained efficiently through extraction with Berlese funnels, collection in water, filtration through Buchner funnels, and separation from glass saucers following moderate drying. The foods used in the tests were (1) freshly fallen wood, conifer needles, and leaves, (2) these same substances in unknown but later stages of decay, (3) known species of wood decayed by known, uncontaminated species of fungi, and (4) individual species of uncontaminated fungi. Ten oribatid species were strictly fungivorous; eight fed primarily upon decaying wood and leaf tissues; and the remainder selected samples of each of the foregoing. The oribatids displayed considerable selectivity toward 20 species of fungi. Wood feeding could take place on Pinus ponderosa inoculated with Lenzites trabea only if at least a 6-week period of decay had elapsed; leaves of sugar maple, Acer saccharum , decayed with L. trabea , were amenable to oribatid feeding within a 2-week decay period. None of the organisms tested could feed on any fresh wood, needle, or leaf tissue, and none was observed feeding on dead oribatids, aphids, Collembola, or other animals.

Further Observations on Fungi Inhabiting Pine Stumps

Growth-rates, both on malt agar and in stump wood, of early stump colonizers such as Fomes annosus, Pemophora gigantea, Stereum sanguinolentum, and Leptographium lundbergii are higher than those of later-colonizing agarics. The initial invasion of stump roots usually proceeds via the stump body by fungi which infect the cut surface. Although stumps may dry out appreciably shortly after felling, in later stages of decay the moisture content of the wood often increases considerably. Stump decomposition is associated with a succession of decay fungi, the ‘Peniophora’, ‘Hypholoma’, and ‘Tricholoma’ stages being distinguished. Several phycomycetes and fungi imperfecti colonize decayed, but not fresh, stump wood. P. gigantea is shown to be a vigorous competitor of F. annosus for initial colonization of stumps: it may also replace F. annosus in stumps. Gliocladium viride and Trichoderma viride compete with wood-rotting basidiomycetes and sometimes replace them in very decayed wood.

An Undescribed Timber Decay of Pitch Pine

SummaryPolyporus amorphus cannot yet be said to be a common fungus in this country since only a few collections are known. It is probable, however, that it is more common than these collections would indicate. Indications are that its range will be southern Canada, New England, and the states bordering on the Canadian line.The fungus causes a characteristic decay of the sapwood of Pinus rigida, and has been collected also on wood of P. Strobus, P. pungens, and Tsuga canadensis.In external appearance the decayed wood is darker in color than sound wood and is of a cinnamon-buff color (Ridgway). The spring wood is completely decayed long before the summer wood disappears. This results in the formation of concentric cavities alternating with the bands of firmer summer wood, and has suggested the name “stringy rot.”Microscopic examination and microchemical tests establish the fact that the fungus first dissolves out the cellulose of medullary rays, then the bordered pits. The lignified structures including the ray tracheids and the vertical tracheids are then attacked and eventually (at least in the spring wood) entirely destroyed. Consequently it is believed that cellulose dissolving enzymes are produced in quantity by the younger mycelium, although probably a lignin dissolving enzyme is not entirely absent. In later stages of decay a lignin dissolving enzyme is produced in greater quantities.