Note * — Chapter III · AGGREGATION OF THE PROTOPLASM WITHIN THE CELLS OF THE TENTACLES.

According to Hofmeister (as quoted by Sachs, ‘Traité de Bot.’ 1874, p. 958), very slight pressure on the cell-membrane arrests immediately the movements of the protoplasm, and even determines its separation from the walls. But the process of aggregation is a different phenomenon, as it relates to the contents of the cells, and only secondarily to the layer of protoplasm which flows along the walls; though no doubt the effects of pressure or of a touch on the outside must be transmitted through this layer. [page 62]