An interesting fact in connection with the wild columbine may be noted. The nectar is deposited in the knob-like bottom of the long tubular spurs, and the entrance is so carefully guarded that only a long and slender proboscis, like that of a moth or a butterfly can reach the nectar. The bumblebees, however, have learned this fact, and bite through the tips of the spurs and steal the nectar. As a consequence, the wild columbine is said to be little visited by the proboscis-bearing insects, and its pollination is seriously interfered with. Sticky excretions.--Some plants have the power of excreting upon their surface a sticky substance like mucilage. This mucilage may be produced by hairs, which are then called "glandular hairs," or it may appear directly on the surface of the plant. When ants or other insects try to cross such a barrier they are not merely stopped but caught. Upon "glandular" plants it is very common to see small insects stuck fast, and it is more than probable that the nourishing material of their bodies is digested and absorbed by the plant. In this way the plant not merely stops the insect, but catches and devours it. A very common illustration of such a plant is the "catchfly," whose name suggests its power. The joints of its stem are long, and near the upper end of each joint is a band of mucilage. This series of sticky bands forms a very effective barrier to any insect trying to crawl up the stem. Isolation.--In some cases plants or their flowers are isolated from creeping insects by water, which forms a most efficient barrier. This has been demonstrated by housekeepers, who in the days of "safes" were accustomed to set the legs of the safe in cans of water to ward off the invasion of ants. Of course, plants standing in the water are well isolated, and usually show no further device for warding off creeping insects. There is an interesting fact connected with one of our water smartweeds, which has to do with our subject. Ordinarily it stands in shallow water, and is perfectly smooth; but when occasionally the water dries up the plant becomes hairy. That this has anything to do with the danger from creeping insects is unlikely, but the hairy covering certainly appears at a very opportune time. The teasel was once extensively cultivated as a fuller's plant, and one or two species of it have become common as wild plants, their dense and prickly flowering spikes looking like swabs for cleaning lamp chimneys. The plant is tall and coarse, and is peculiar in that its large opposite leaves unite by their bases about the stem to form a cup. In this way a series of cups is developed on the stem, and in each cup there is water. When a creeping insect crawls over the edge of the cup he sees the stem rising from a pool of water which must be crossed. As there is a series of such pools it is very unlikely that any such insect reaches the showy cluster of flowers.