MECHANICAL STRESS AND CELL WALL ORIENTATION IN PLANTS. II. THE APPLICATION OF CONTROLLED DIRECTIONAL STRESS TO GROWING PLANTS; WITH A DISCUSSION ON THE NATURE OF THE WOUND REACTION

This paper describes an attempt to present living stem tissue with defined mechanical stress in a spatial configuration which can be easily interpreted in section. We have applied compressive stress to a growing Coleus internode in vivo, using stainless-steel spring-clips which act through a double-edged glass interface of known area. We have found that cambial activity consisting of cell division and enlargement continues even under applied compressive stress ranging up to 20 atm. Tissue reactions to applied stress are discussed in terms of the equilibration of forces propagating through the tissue before, during, and after the presentation of externally applied stress.