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Early embryonic development, from the first cleavage to the germ-disk stage, in the theridiid spider Achaearanea japonica was examined by light and electron microscopy. The eggs are syncytial during the first four cleavages, and then invaginations of cell membranes fuse to generate the blastomeres at the sixteen-nucleus stage. The cleavage pattern is a modified type of total cleavage. It appears that radial bundles of microtubules that radiate from the perinuclear cytoplasm may participate in the migration of cleavage nuclei for the formation of the blastoderm. The large yolk granules are sequestered by cell membranes from the blastomeres or blastoderm cells into the interior of the embryo together with various organelles and glycogen granules. Most of the blastoderm cells converge in the upper hemisphere to form the germ disk, whereas a few cells remain in the lower hemisphere. The embryo at the germ-disk stage contains many spherical germ-disk cells. Almost no large yolk granules are found in these cells, but the flat remaining cells each contain several large yolk granules. These remaining cells may preserve a flat shape to cover the surface of the embryo that does not include the germ disk. © 1995 Wiley-Liss, Inc.

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The purpose of this paper is to develop a Tsunami evacuation simulation model. In this model, which uses the concept of MultiAgent Systems, each evacuee has an age, an evacuation speed, a number of neighborhood obstacles, a fatigue level and a consciousness of disaster mitigation as attribute data. Evacuation behavior is decided by interaction of these data and environment around the evacuee. This model was applied to Tomoura historical built-up area in Tokushima to evaluate six scenarios of disaster mitigation. From the results of these simulations, it was found that giving the Tsunami alert to all inhabitants quickly was the most important factor.� Kojiro WATANABE and Akio KONDO 74 637 627-634 2009