The Bladderworts (_Utricularia_), of which several species may be found floating in boggy pools, are rootless, limp plants with finely divided leaves, among which are numerous little bladders (in reality strangely modified leaflets), and upright stems bearing pretty yellow Snapdragon-like flowers. The bladders do not help the plant to float, and appear to have for their sole function the securing of animal food. In the Common Bladderwort (_U. vulgaris_) they are about 1/10 inch long. At the upper end is a little hinged door, which is kept closed as by a spring against a thickened rim or door-frame. Outside the door are a few stiff hairs, a convenient perching-place for small aquatic creatures such as the minute Crustaceans known as Water Fleas. Should one of these try to explore the bladder, the door opens easily, but closes at once behind the rash wanderer, imprisoning it. The Bladderworts do not _digest_ the victims which they secure in this manner, but when the bodies are decomposed by means of bacteria, the products of decomposition are absorbed. How fatal this mousetrap arrangement is to Water Fleas can be determined by dissecting the bladders of the plant. Thus far, then, as regards some of those peculiar members of our flora which make their living by the unusual method of stealing their neighbour’s goods, or which eke out their existence by the capture of animal food. Let us now take another line of exploration and consider the conditions which prevail on the loftiest portions of our islands, and how these affect the vegetation. Mountain-tops are always attractive and interesting places--the keen rarefied air, the freedom and openness of the summits, fill us with exhilaration. Our own mountains are not lofty; nowhere in the British Islands is a height of a mile attained. But we have only to ascend to a couple of thousand feet to note a great change in the vegetation. The plants of the lower grounds to a great extent die out (though some accompany us to our highest summit), and the vegetation takes on a low compact form, which becomes more emphasized as we ascend farther, till in sheltered nooks alone do we find any plants more than a few inches in height. Furthermore, we notice an incoming of new plants unknown at lower levels, which search will show us to be confined to the mountains, each of them having a more or less definite limit below which (also above which, though our mountains are not high enough to render this point well marked) it is not found.