After contraction has endured for a greater or less time, dependent upon circumstances which we do not well understand, re-expansion of the leaves is effected at an insensibly slow rate, whether or not any object is enclosed, both lobes opening in all ordinary cases at the same time, although each lobe may act to a certain extent independently of the other. The re-expansion is not determined by the sensitive filaments, for these may be cut off close to their bases, or be entirely removed, and re-expansion occur in the usual manner. It is believed that the several layers of cells forming the lower surface of the leaf are always in a state of tension, and that it is owing to this mechanical state, aided probably by fresh fluid being drawn into the cells, that the lobes begin to separate as soon as the contraction of the upper surface diminishes. Six known genera, Drosophyllum, Roridula, Byblis, Drosera, Dionæa and Aldrovanda comprise the Droseraceæ, all of which capture insects. The first three genera effect this purpose solely by the viscid fluid secreted from their glands, and the last, like Dionæa, which has already been described, through the closing of the blades of the leaf. In these last two genera rapid movement makes up for the loss of viscid secretion. But of all the genera none is more interesting than the typical Sundews. Growing in poor peaty soil, and sometimes along the borders of ponds where nothing else can grow, certain low herbaceous plants, called Droseras, abound. So small and apparently insignificant are they, that to the ordinary observer they are almost unnoticed. But they have peculiarities of structure and nature that readily distinguish them. Scattered thickly over their leaves are reddish bristles or tentacles, each surmounted by a gland, from which an extremely viscid fluid, sparkling in the sunlight like dew, exudes in transparent drops. Hence the common name of Sundew by which the half-dozen species found in the United States east of the Mississippi River are known. A one-sided raceme, whose flowers open only when the sun shines, crowns a smooth scape, which is devoid of tentacles. _Drosera rotundifolia_, our commonest species, has a wide range, being indigenous to both Europe and America. In the United States it extends from New England to Florida and westward, and is occasionally associated with _Drosera longifolia_, a form with long strap-shaped leaves, but whose distribution is mostly restricted to maritime regions, from Massachusetts to Florida. [Illustration: ROUND-LEAVED SUNDEW. Leaves Acting as Stomachs.]