DIFFERENTIATION,ORGANOGENESIS, AND THE TECTONICS OF CELL WALL ORIENTATION. II. SEPARATION OF STRESSES IN A TWO-DIMENSIONAL MODEL

This paper describes a polarographic technique for the separation of tension and compression stresses in a two-dimensional plastic model of a sectioned cotton ovule. Compression and tension stress trajectories in the model comprise two families of lines which are mutually perpendicular and which, in the “nucellar” region of the model, coincide with cell wall patterns seen in sectioned ovules. This arrangement of stresses is demonstrated, by direct manipulation of the model, to be dependent on the pressure of the integuments. The integuments insure that compressive stresses generated during the growth of the nucellus do not collapse the embryo sac but pass around it, leaving it as a compression-free space within the growing ovule.