The seeds of Cucwubit maximas contain protein bodies with electrondense globoid crystals. Because of their density globoid crystals are ideal material for energy-dispersive x-ray (EDX) analysis studies of elemental composition. Fixation trials were carried out to test globoid crystal extraction during glutaraldehyde fixation, water washing, and ethanol dehydration. Glutaraldehyde fixation without subsequent washing or dehydration alone produced no significant changes in elemental composition of cotyledon globold crystals. If glutaraldebyde fixation was followed by water washes or ethanol debydration there was some loss of the major globoid crystal elements but the relative percentages of the elements P, K, Ca, and Mg remained relatively unchanged. In this paper results of a study of the P, K, Mg, and Ca content of globold crystals in different tissues of squash embryos are presented. The globoid crystals in the radicle were found to be the least dense in the embryo. Globoid crystals from all embryo regions contained P, K, and Mg. In the various embryo regions P and Mg maintained relatively constant proportions of the globoid crystal composition while K and Ca varied. Of particular significance is the distribution of Ca which is generaly an immobile element. Calcium was found in highest amounts in the globoid crystals of the radicle and stem regions while globoid crystals in much of the cotyledon contained little, if any, Ca. The Ca storage thus seems to be spatially arranged in a manner that would aid early growth of the root-shoot axis.In order for us to understand the nutritional state GLOBOID CRYSTAL COMPOSITION tained from a single fruit grown at CSIRO, Adelaide, South Australia.Two seeds of similar size from the Stoke's seed supply (seeds I and 2) and two seeds from a fruit grown at CSIRO (seeds 3 and 4) were selected for EDX2 analysis. The seed coats were removed and tissue was sampled from the radicle, stem, cotyledon base, cotyledon center, cotyledon side, and cotyledon tip of each seed. Since the embryo axis of squash is very short, the stem sample was selected as the portion of the axis to which the cotyledons were attached. The cotyledon base sample was that portion of the cotyledon immediately adjacent to the cotyledonary node. A 3-mm2 region at the center of the cotyledon was used as the cotyledon center sample. The cotyledon side sample came from a region (2 x 5 mm) at the edge of the cotyledon, midway between the cotyledon base and the cotyledon tip. For the cotyledon tip sample a 2-mm2 region of tissue was taken from the edge of the cotyledon in the region furthest removed from the cotyledonary node.Tissues from the cotyledon and stem regions were sliced 0.5 to 1 mm thick prior to fixation. The samples were prepared for EDX analysis according to the method of Lott (11). Tissues from the dry seeds were fixed in 5% glutaraldehyde in distilled H20, dehydrated, infiltrated with Spurr's low viscosity epoxy resin, and polymerized. Sections, 150 to 170 nm thick, were mounted on copper grids ha...