Observing the embryo in dust-like seeds with a rigid coat presents a particular challenge, because it is not possible to use conventional techniques applied to normal-sized seeds. A new combination of softening and clearing techniques, which is remarkably effective for direct observations of embryos in minute seeds, is reported here. Moreover, no special seed treatment is required prior to application of this combination of techniques, and good results are obtained from living and preserved material. Dust-like seeds of Cytinus hypocistis and Cytinus ruber with a rigid coat were treated successively with Franklin's and with Jeffrey's softening fluids, and then with Herr's clearing fluid. The combined action of the two softening fluids caused sufficient seed coat rupture to allow Herr's fluid to clear seed tissues, permitting effective observation of the embryo. This technique should be applicable to a wide range of species with dust-like seeds, and its possibilities for biological studies are numerous.
