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In Langendorff preparations of rat heart, hyperkinetic ventricular arrhythmias (HVA) have been induced by an ischaemic perfusion (coronary flux 0.5 ml min ; pressure 8 mmHg) and following reperfusion at basal conditions (coronary flux 8 ml min ; pressure 50 mmHg). Crude methanolic extracts of Harpagophytum procumbens secondary roots and harpagoside showed a significant, dose-dependent, protective action toward HVA induced by reperfusion.

The following 13 species of predacious mites of the family Phytoseiidae are recorded from various plants in Kenya: Amblyseius albizziae sp. nov., A. kenyae sp. nov., A. natalensis Van der Merwe, A. lokele Pritchard & Baker, A. largoensis (Muma), A. rykei Pritchard & Baker, A. teke Pritchard & Baker, Typholdromus kikuyuensis sp. nov., T. magdalenae Pritchard & Baker, Phytoseius amba Pritchard & Baker, p. ferox Pritchard & Baker, Iphiseius degenerans (Berlese), I. gongylus Pritchard & Baker. The new species and the male of A. natalensis are described.

Cu is a microelement that plays an exclusively catalytic role in plants in numerous enzymes and acts in nitrite reduction as a component of nitrite-reductase. Copper compounds are used in agriculture against a large number of parasitic fungi so that very high concentrations of Cu can be found in the aerial parts of plants and in the soil. The effects of repeated spraying with copper oxychloride solution on the development and active principle content of Datura metel L. were studied.

Summary Effects on germination, growth and active principle contents of Achillea millefolium L. of an increase of cadmium concentration in soil and in atmosphere were investigated. Soil pollution reduced germination and growth. No significant differences were found in GLC analysis of all plants extracts.

The effects of Cd++ concentration increment in soil and/or in atmosphere, on germination, growth and alkaloid contents of Datura metel L. were investigated. We observed a significant reduction of growth following addition of Cd++ in soil. Minor effects on growth were evident when the plants were sprayed with CdCl2 solution (10mgCd++/l). Scanning electron microscope observation showed stomata widely open and conspicuous cuticular striations in the foliar epidermis of polluted plants. GLC analysis of extracts evidenced a significant variation in active principle content among plants undergoing different treatments.

Histological characteristics, as observed by scanning electron microscope, of the secondary roots of Harpagophytum procumbens DC. (Pedaliaceae), a drug widely used in South African traditional medicine, specially by Bushmen, Hottentots and Bantu, are described in detail. It has been possible to reveal some morphological elements that, together with superficial granular material containing harpagoside and harpagide, allow drug identification.

Effects of the crude methanolic extract of Harpagophytum procumbens secondary roots and two of its active principles, harpagoside and harpagide, on some smooth muscle in vitro have been studied. The results obtained show how the action of H. procumbens is due to a complex interaction between the various active principles contained in the drug and suggest that they, especially harpagoside, interfere with the mechanisms that regulate the influx of calcium in the cells.

To achieve a systematic identification and differentiation of the species belonging to the various sections of this genus, the surface characteristics of species of section Stramonium (D. stramonium L., D. inermis Jacq., D. tatula L., D. stramonium L. var. godronii Danert, D. ferox L., D. quercifolia H.B.K.) have been examined by Scanning Electron Microscope (SEM).Cell shape and size, number and disposition of both protective and glandular hairs, stomatal, vein-islet and veinlet termination numbers allow one to characterize the different samples examined.