Vol. 11 No. 1 (1976)

. Widmanstatten microstructures are often observed in Ag-Sn dental alloys, after they underwent slow cooling for homogenization temperature. This structure appears when the alloy contains silver or silver equivalent between 75 and 80 wt %. Hatchet mark structure somewhat similar to Widmanstatten structure may be generated during the metallographic preparation of the specimens. These marks are actually mechanical twins resulted from the plastic deformation during the process of grinding and polishing. Ringkasan. Struktur Windmanstatten yang timbul pada logam dental Ag-Sn disebabkan oleh proses…

. The development of sclerotia, structure and microconidia of Sclerotinia Sclerotiorum are described. Sclerotial initials are formed by hyphal strands which branched dichotomously to give a small knot and bound the hyphae together and then became solid masses which were spherical to irregular in shape. The mature sclerotium are blackand consists of three distinct regions, the outermost layer is a rind, within the rind is a cortex and the centre of the sclerotium is a medulla. Microconidia are readily produced in cultures of the fungus but no evidence was found of microconidial clusters…

. In Arenga Porphyrocarpa the vegetative axis is terminalised by the onset of the hapaxanthic flowering axis. This is accompanied by a reduction of leaf size. The part of the axis beyond the last node transforms into a female inflorescence which consists of a system of rachillae on which the individual flowers are attached. Male inflorescences develop afterwards on the remaining nodes but may also develop from the most distal node later on. Additional female inflorescence may develop at lower nodes. Monopodial branching is not confined to the reproductive axis only but occurs also in the…