Fig.1. Location of crystals in the planulae and polyps. (A,B) Comparison of the same live planula (slightly different because of movement) viewed by (A) brightfield and (B) polarized light microscopy. The crystals are located in the endoderm (En); the ectoderm (Ec) is devoid of crystals. The white bars in B indicate the margin of the ectoderm. Scale bar, 100µm. (C) Posterior end of planula as seen with DIC microscopy. The mesoglea (Mg) forms the boundary between the endoderm (En) and ectoderm (Ec). The nucleus (n) of the gastrodermal cell (GDC; cell area indicated by a dashed line) is suspended in a large vacuole (v) by thin strands of cytosol. Arrows indicate crystals within the large vacuoles. The position of crystals do not correspond to those of nematocysts (nc). Scale bar, 10µm. (D,E) A living polyp from a colony growing on a slide, viewed by (D) polarized light and (E) DIC microscopy. The mouth, located at the tip of the hypostome (H), opens into the gastrovascular cavity (GvC). Crystals are located in the endodermal cells of the body column (BC) and stolons (S) of the polyps; few, however, are located in the hypostome or tentacles (T). The ectoderm (Ec) is devoid of crystals. Scale bar, 200µm.