Sep 13, 2024
Model of the origin of arcs in oblique sections of a regularly twisted fibrous system. A pyramidal trunk superposes a series of rectangular cards of constant thickness. Parallel straight lines are drawn on each card and their direction changes by a small and constant angle from one card to the following one. The twist is chosen left-handed, as in most biological materials of this kind. Some arcs were underlined on the oblique face, on the left. The width of the arc series depends on the obliquity and one also observes the opposite orientations of the arc concavities on the left and on the right. Yves Bouligand, Liquid crystals and biological morphogenesis: Ancient and new questions