The _Podura plumbea_ (or "Spring Tail"), common enough in England, and found under all kinds of stones, will give the reader an idea of the flea of the glaciers. On comparing these two species, we remark, first, that the _Podura plumbea_ is somewhat longer and thicker in body than the flea of the glaciers (see Fig. 16; _a_, natural size; _b_, enlarged); but it is more particularly by the length of its antennæ that we distinguish it. It owes its specific name of _Plumbea_ to the livid blue or leaden colour of the scales which cover its body. These scales resemble those of butterflies; only they are much smaller, more finely situated, and very variable in form and size (Fig. 17). In catching it great care is required, for it is so easily crushed; it is, besides, very soft to the touch, though, when examined with a microscope, it is seen to bristle all over with hairs, apparently very hard. [Illustration: FIG. 17.] Our _poduræ_ have also the faculty of leaping, and cling by thousands to humid places, especially to mosses and the under-surface of stones. The mechanism of their leap is explained by the presence of a forked, flexible, and elastic appendage, lodged in a kind of ventral groove beneath the last segments; by projecting this rapidly behind, the whole body of the animal is thrown forward. At the slightest contact the insect folds up its caudal appendage under its belly, and you would then suppose it did not possess one. This circumstance explains why, in many books of natural history of good repute, the _poduræ_, and especially so common a species as the _Podura plumbea_, are represented without this characteristic instrument. HERBACEOUS PLANTS WHICH BEST ENDURE THE COLD OF WINTER. The "way to look at things," which is the true foundation of science, varies, not only according to a man's degree of intellectual cultivation, but according to his social condition or profession. The herborist has eyes only for the plants in which he deals,--the "simples" which, as we read in old Gerarde, wrought such wonderful cures in the days of our forefathers,--and from the most exquisite flowers he turns with indifference. The gardener, on the other hand, is wholly absorbed by his love and his hate,--his charming exotics, and his troublesome weeds. The latter he regards with much the same feelings as a society wholly composed of honest men would regard an infusion of the "dangerous elements;" for weeds, like rogues, take what is not their own, and deprive others of their means of sustenance. But to classify plants according to their virtues or vices is not worthy of science, exclaims the rigid botanist. Would you mingle vile self-interest with the pure study of the vegetable kingdom? Remember that all selfish feelings ought to be banished from the sublime sanctuary of analysis and synthesis.