MECHANICAL STRESS AND CELL WALL ORIENTATION IN PLANTS. I. PHOTOELASTIC DERIVATION OF PRINCIPAL STRESSES. WITH A DISCUSSION OF THE CONCEPT OF AXILLARITY AND THE SIGNIFICANCE OF THE “ARCUATE SHELL ZONE”

This study describes a further investigation into the meaning of patterns of cell wall orientation in plants and outlines a modified method for the generation of patterns of principal stresses in a two-dimensional model. Evidence from simple photoelastic models is presented which supports the concept that the initial location of a presumptive axillary bud primordium may be controlled by mechanical stress in the region of the leaf axil.