Experiments with the Stipes of Fucus and Laminaria

Abstract

1. The breaking stress or ultimate strength of a number of algae has been determined by the method of fracture by tension. The magnitude of the breaking stress was not correlated with exposure due to the locality or to the position on the shore. 2. The elastic limits and the extensibility have been determined for Fucus, Laminaria, Ascophyllum and Halidrys in a few cases; and, for comparison, the petiole of Aucuba with collenchymatous and of Aspidistra with lignified tissue. 3. Fucus has relatively the least power of extension and the greatest resistance to stretching of the algae examined. 4. Ascophyllum and Laminaria have much greater power of extension and less power of resistance to it. 5. Attention has been drawn to the long endurance of the base of the lamina of Ascophyllum to a load which caused stretching well beyond the elastic limits. 6. Some quality in the cell wall is invoked to account for (a) the form of break on rupture by tension, (b) the breaking stress, and (c) the characteristics of the elasticity and extensibility.