This paper deals with some preliminary technical experiments on cultures of the embryos and organs of Tachypleus tridentatus. In embryo culture, using the embryos at various stages of development, embryonic areas with hardly any yolk remaining in them were cultured in various media and by various methods (Series A); hemispheres of embryos containing the embryonic area (Series B) and whole embryos without egg membranes (Series C) were cultured in sterilized sea water. The suitability of the culture media and methods is described; the medium containing calf serum or 199, and the hanging-drop method were found to be the most appropriate of those used in respective series of experiments. The changes in external and internal structures of the explants from embryos at various developmental stages cultured in various media and by various methods are described; dorsal closure, secretion of inner egg membrane, thickening of the cell layer and the elongation of limb buds were all observed in the Series A experiments. In Series B and C, coelom formation and also normal development of the embryos cultured after the 2nd embryonic moulting were observed. In organ culture, fragments of the embryonic heart were cultured in various media and by various methods. The hanging-drop method resulted in longer survival than the method using agar media.