Page:Popular Science Monthly Volume 19.djvu/174

162 When the seeds are fully ripe, the capsule opens by three valves and allows them to escape.

In the dog-violet (Viola canina, Fig. 3) the case is very different. The capsules are less fleshy, and, though pendent when young, at



maturity they erect themselves (Fig. 3, c), stand up boldly above the rest of the plant, and open by the three equal valves (Fig. 4) resembling an inverted tripod. Each valve contains a row of three, four, or five brown, smooth, pear-shaped seeds, slightly flattened at the upper,



wider end. Now the two walls of each valve, as they become drier, contract, and thus approach one another, thus tending to squeeze out the seeds. These resist some time, but at length the attachment of