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Bees trained to forage at a place specified by landmarks do not construct a cartesian map of the arrangement of landmarks and food source. Instead they store something like a two-dimensional snapshot of their surroundings taken from the food source. To return there, bees move so as to reduce discrepancies between the snapshot and their current retinal image. A computational model embodying these principles mimics the bees' behaviour.

Abstract: Parasitism ofCoccinella septempunctata L. byPerilitus coccinellae (Schrank) varies seasonally with an 11% overall rate among beetles overwintering in the Hackensack Meadowlands, which is less than that reported in Europe.P. coccinellae may parasitizeC. 7-punctata twice yearly. FemaleC. 7-punctata were parasitized more heavily than males. Although parasitism byP. coccinellae varied significantly among host species, it was not significantly different among 3 habitats. High host density favored greater parasitism in 3 coccinellid species. Rearing for parasite cocoons, consistently showed lower parasitism rates than did dissection for parasitized larvae. Overwintering survival of cagedC. 7-punctata near Stillwater, OK, varied between years averaging 53,5%. Infection of overwinteringC. 7-punctata byBeauveria bassiana (Balsamo) was 1,6% in 1978–1979.

Abstract: The preference in the choice of hibernacula of the convergent lady beetle,Hippodamia convergens Guérin-Meneville, was investigated with regard to morphological aspects of 2 introduced range grasses,Panicum coloratum (L.), andEragrostis curvula (Schrad.) Beetles strongly preferred tussocks with a ratio in the range of 1.0–3.0 stems per cm2 for lovegrass. Preference for klein grass tussocks ranging from 110–130 stems/clump was found. No preference was shown for a particular tussock circumference. It was demonstrated that tussocks could successfully be designated as suitable for beetle aggregation.

Insects generally have eyes that are close together and lenses with a very short focal length. In consequence neither stereoscopic nor focus cues can be used to measure the distance of objects that are further than a very few centimetres. To do this insects must rely on information provided by retinal image size or by motion parallax. If an insect knows how large an object appears to be at one distance, it can use image size to compute any other object distance. This method is probably used by some male hoverflies when tracking conspecifics (Collett & Land, 1975). Bulldog ants snap at an image of constant retinal size, and so open their jaws when an appropriately sized prey object comes within range (Via, 1977). The distance of an object can also be specified by the way in which its image travels across the retina or changes size when an insect moves a known distance or at a known speed. To date only stationary locusts have been shown to exploit motion parallax, which they do by performing a specialized side-to-side head and body movement (Wallace, 1959; Collett, 1978). Very little, however, is known about the ways in which freely flying insects measure their distance from stationary objects. We were interested in studying this question in honey-bees because they clearly have a good appreciation of the arrangement of stationary features in their environment, which they will demonstrate all day long as they fly between a food source and their hive. Bees can learn to locate a source of food using near-by landmarks and to do this they must know their distance from such landmarks (Lauer & Lindauer, 1971 ; Anderson, 1977). In this paper we show that honey-bees use both motion parallax and image size or change in image size in determining how far they are from a single landmark.

Thymidine uptake of unstimulated and of phytohemagglutinin (PHA)-, streptokinase-streptodornase (SK-SD)- and candida extract (candida)-stimulated lymphocytes of normal infants less than 20 months old was evaluated. Thymidine uptake of unstimulated and PHA-stimulated young infants' lymphocytes was avid, resembling that of newborn cells. Over periods of weeks to months, infantile lymphocytes demonstrated transition in unstimulated and PHA-induced thymidine uptake from response patterns like cord blood cells to ones more characteristic of adult lymphocytes. Candida- and SK-SD-induced thymidine uptake of lymphocytes from very young infants was likewise apparently quite avid, resembling cord blood cells. However, factoring out high unstimulated thymidine uptake by conversion of data to stimulation indexes clarified differing paces of acquisition of transformation responsiveness of the two naturally acquired infectious antigens. Specific lymphocytes reactivity to SK-SD was quite low in all groups of infants compared with candida-induced transformation, which in some infants acquired adult proportions.

Human peripheral blood lymphocytes stimulated with Histoplasma capsulatum yeasts were exposed in culture to graded concentrations of ketoconazole or amphotericin B and subsequently assessed for membrane integrity, thymidine uptake, and blastogenesis. Lymphocyte reactivity varied with concentration and duration of exposure to ketoconazole. Overt membrane toxicity resulted from exposure to 40 micrograms of ketoconazole per ml for 5 days, diminished thymidine uptake occurred with concentrations as low as 5 micrograms/ml, and 15 to 20 micrograms/ml caused a marked decrease in thymidine uptake and eventually diminished blastogenesis. The antilymphocyte action of ketoconazole was neutralized by increasing the concentration of human serum in cultures to 40% regardless of its cholesterol content. Amphotericin B activity was qualitatively similar but less pronounced.

Human peripheral blood mononuclear cells were cultured with either replicating yeast phase Histoplasma capsulatum, intact dead yeasts or soluble yeast phase autolysate antigen for induction of lymphocyte blastogenesis. H. capsulatum replicated to the same extent in cultures of lymphocytes from histoplasmin skin test-positive and negative cell donors, but stimulated far greater blastogenesis in the former. Dead H. capsulatum yeasts, which were more easily quantified, caused nearly as much specific blastogenesis as live yeasts. Blastogenesis was induced by as few as 1 dead yeast per 10,000 lymphocytes, indicating the antigenic potency of Histoplasma yeasts. Specific blastogenesis was also caused by soluble yeast autolysate. Thus, replicating H. capsulatum yeasts, dead yeasts and autolytically released soluble yeast phase antigen each stimulated specific blastogenesis of lymphocytes from persons sensitized to H. capsulatum in vivo.

Vesicular stomatitis virus contains single-stranded ribonucleic acid of molecular weight 3.6 × 106and three major proteins with molecular weights of 75 × 103, 57 × 103, and 32.5 × 103. The proteins have been shown to be subunits of the surface projections, ribonucleoprotein, and matrix protein, respectively. From these values and from estimates of the proportions of the individual proteins, it has been calculated that the virus has approximately 500 surface projections, 1,100 protein units on the ribonucleoprotein strand, and 1,600 matrix protein units. Possible models of the virus are proposed in which the proteins are interrelated.

Treatment of suspensions of vesicular stomatitis virus with Tween-ether results in a rapid and considerable loss of infectivity (ca. 4 logs in 2 min), but the residual infectivity is comparatively stable to further treatment with ether. The infectivity remaining after the short exposure to Tween-ether is not due to virus for the following reasons. (i) It is much less infective for tissue cultures than for mice, whereas the intact virion is equally infective for both hosts. (ii) The residual infectivity is much less stable than virus infectivity in both sucrose and tartrate gradients. (iii) Virus immune serum does not neutralize its activity. (iv) The infectivity is associated with material which sediments further in sucrose gradients and has a greater buoyant density in tartrate gradients than the virion. Experiments with 32P-labeled virion showed that the infective substructure contains ribonucleic acid with the same sedimentation characteristics as that extracted from the virion. Electron microscopy shows that the infective component has the same overall bullet-like structure as the virion but lacks the outer envelope and fringe structure.

The comparative availability to Lolivm perenne of 32P myo-inositol hexaphosphate (IH32P) and KH232PO. added to soil could be determined unequivocally from the 32P count of leaf material even when dry matter yields and total P content were not significantly different from the control.IH32P was equivalent to KH232PO4. in a soil with a low P retention at 200 p.p.m. P but not at 20 p.p.m. P. IH 32P was totally unavailable in two soils with high P retention at 200 p.p.m. and 20 p.p.m. P, whereas uptake of KH232PO4. was observed in each instance.