Über die Struktur pflanzlicher Karotinkriställchen

Summary Crystals of carotene in plant cells (carrot root, corona ofNarcissus etc.) have been attributed to the orthorhombic or the hexagonal system. However, an optical investigation showed that they have a lower symmetry. In the case of the crystals in the corona ofNarcissus, the structural identity with synthetic-carotene is proved by X-ray and electron diffraction analysis. Although the geometry of the electron diffraction patterns is almost indistinguishable from hexagonal, its reflections can be identified with those from the planes of the monoclinic lattice of-carotene. The face of the plate-shaped crystals corresponds to (102).