Page:Insectivorous Plants, Darwin, 1899.djvu/26

 respects they do not differ essentially from the oval ones, and in one specimen I found every possible transition between the two states. In another specimen there were no long-headed glands. These marginal tentacles lose their irritability earlier than the

(Drosera rotundifolia.) Longitudinal section of a gland ; greatly magnified. From Dr. Warming.

others, and, when a stimulus is applied to the centre of the leaf, they are excited into action after the others. When cut-off leaves are immersed in water, they alone often become inflected.

The purple fluid, or granular matter which fills the cells of the glands, differs to a certain extent from that within the cells of the pedicels. For, when a leaf is placed in hot water or in certain acids, the glands become quite white and opaque, whereas the cells of the pedicels are rendered of a bright red, with the exception of those close beneath the glands. These latter cells lose their pale red tint; and the green matter which they, as well as the basal