The oscillatory control of cell differentiation in Nectria?

This paper analyzes a spatially periodic phenomenon in the fungus Nectria Cinnabarina, first reported by Bourret, Lincoln, and Carpenter1. This is the apparently random occurrence of discrete alternative morphologies in the mycelium of Nectria when growth begins from a point-innoculum on agar. These morphologies are topologically distinct zonation patterns of conidiating (sporulating) hyphae, including concentric closed rings, a single spiral, a pair of disjoint but parallel spirals, and "intermediate" cases Involving one or more radial dislocations. The phenomenon is redescribed in terms of a mapping of the unit circle into itself, to facilitate a speculative interpretation of its origin. This interpretation rests on the conjecture that the growing hyphae of Nectria harbor a self-exciting cytochemical oscillation which influences the induction of embryonic cells to a nonsporulating maturity.