Passing now in the other direction, up the stream from the bridge, the hedges after a while cease, and the brook winds through the open fields. Here there is a pond, to which at night the heron resorts; for he does not care to trust himself between the high hedgerows. In the still shallow, but beyond reach, there floats on the surface a small patch of green vegetation formed of the treble leaves of the water crow-foot. Towards June it will be a brilliant white spot. The slender stems uphold the cup-like flowers two or three inches above the surface, the petals of the purest white with a golden centre. They are the silver buttercups of the brook. Where the current flows slowly the long and somewhat spear-shaped leaves of the water-plantain stand up, and in the summer will be surmounted by a tall stalk with three small pale pink petals on its branches. The leaf can be written on with a pencil, the point tracing letters by removing the green colouring where it passes.

Far larger are the leaves of the water-docks; they sometimes attain to immense size. By the bank the 'wild willow,' or water-betony, with its woody stem, willow-shaped leaves, and pale red flowers, grows thickly. Across where there is a mud-bank the stout stems of the willow herb are already tall. They quite cover the shoal, and line the brook like shrubs. They are the strongest and the most prominent of all the brook plants. At the end of March or beginning of April the stalks appear a few inches high, and they gradually increase in size, until in July they reach above the waist, and form a thicket by the shore. Not till July does the flower open, so that, though they make so much show of foliage, it is months before any colour brightens it. The red flower comes at the end of a pod, and has a tiny white cross within it; it is welcome, because by August so many of the earlier flowers are fading. The country folk call it the sod-apple, and say the leaves crushed in the fingers have something of the scent of apple-pie.

Farther up the stream, where a hawthorn bush shelters it, stands a knotted fig-wort with a square stem and many branches, each with small velvety flowers. If handled, the leaves emit a strong odour, like the leaves of the elder-bush; it is a coarse-growing plant, and occasionally reaches to a height of between four and five feet, with a stem more than half an inch square. Some ditches are full of it. By the rushes the long purple spike of the loose-strife rises, and on the mud-banks among the willows there grows a tall plant with bunches of flower, the petals a bright yellow: this is the yellow loose-strife. Near it is a herb with a much-divided leaf, and curious flowers like small yellow buttons. Rub one of these gently, and it will give forth a most peculiar perfume—aromatic, and not to be compared with anything else; the tansy once scented will always be recognised.

The large rough leaves of the wild comfrey grow in bunches here and there; the leaves are attached to the stem for part of their length, and the stem is curiously flanged. The bells are often greenish, sometimes white, occasionally faintly lilac; they are partly hidden under the dark-green leaves. Where undisturbed the comfrey grows to a great size, the stems becoming very thick. Green flags hide and almost choke the shallow mouth of a streamlet that joins the brook coming from the woods. Though green above, the flag where it enters its sheath is white.

Tracing it upwards, the brook becomes narrower and the stream less, though running more swiftly; and here there is a marshy spot with willows, and between them some bulrushes and great bunches of bullpolls. This coarse grass forms tufts or cushions, on which snakes often coil in the sunshine. Yet though so rough, in June the bullpoll sends up tall slender stalks with graceful feathery heads, reed-like, surrounded with long ribbons of grass. In the ditches hereabout, and beside the brook itself, the meadow-sweet scents the air; the country-folk call it 'meadow-soot.' And in those ditches are numerous coarse stems and leaves which, if crushed in the fingers, yield a strong parsnip-like smell. The water-parsnip, which is poisonous, is said to be sometimes gathered for watercress; but the palate must be dull, one would think, to eat it, and the smell is a sure test. The blue flower of the brooklime is not seen here; you must look for it where the springs break forth, where its foliage sometimes quite conceals the tiny rill.

These flowers do not, of course, all appear together; but they may be all found in the summer season along the brook, and you should begin to look for them when the brown scum, that sign of coming warmth, rises from the bottom of the waters. Returning to the pond, it may be noticed that the cart-horses when they walk in of a summer's day paw the stream, as if they enjoyed the cool sound of the splash; but the cows stand quite still with the water up to their knees.

There is a spot by a yet more quiet bridge, where the little water-shrews play to and fro where the bank overhangs. As they dive and move under water the reddish-brown back looks of a lighter colour; when they touch the ground they thrust their tiny nostrils up just above the surface. There are many holes of water-rats, but no one would imagine how numerous these latter creatures are. One of Hilary's sons, Hugh, kept some ferrets, and in the summer was put to it to find them enough food. The bird-keepers brought in a bird occasionally, and there were cruel rumours of a cat having disappeared. Still there was not sufficient till he hit on the idea of trapping the water-rats; and this is how he did it.

He took three small twigs and ran them into the bank of the brook at the mouth of the water-rat's hole and just beneath the surface of the stream. These made a platform upon which the gin was placed—the pan, and indeed all the trap, just under the water, which prevented any scent. Whether the rat came out of his hole and plunged to dive or started to swim, or whether he came swimming noiselessly round the bend and was about to enter the burrow, it made no difference; he was certain to pass over and throw the gin. The instant the teeth struck him he gave a jump which lifted the trap off the twig platform, and it immediately sank in the deep water and soon drowned him; for the water-rat, though continually diving, can only stay a short time under water. It proved a fatal contrivance, chiefly, as was supposed, because the gin, being just under the water, could not be smelt. No fewer than eleven rats were thus captured in succession at the mouth of one hole. Altogether 150 were taken in the course of that summer.

Hugh kept a record of them by drawing a stroke with chalk for every rat on the red brick wall of the stable, near his ferret-hutch. He only used a few traps—one was set not at a hole, but at a sharp curve of the brook—and the whole of these rats were taken in a part of the brook about 250 or 300 yards in length, just where it ran through a single field. The great majority were water-rats, but there were fifteen or twenty house-rats among them: these were very thin though large, and seemed to be caught as they were migrating; for sometimes several were trapped the same day, and then none (of this kind) for a week or more. Three moorhens were also caught; a fourth was only held by its claw in the gin; this one, not being in the least injured, he let go again.

It had been observed previously that the water-rats, either in making their burrows or for food, gnawed off the young withy-stoles underneath the ground in the withy-beds, and thus killed a considerable amount of withy; but after all this slaughter the withy-beds recovered and bore the finest crop they ever grew. But who could have imagined in walking by the brook that only in its course through a single meadow it harboured 150 rats? Probably, though, some of them came up or down the stream. The ferrets fared sumptuously all the summer.