For nearly an hour the progress was very slow; but when the ring-snake was nearly all swallowed except a few inches of tail, these became so tight a muzzle that Ophio in turn was the victim.  Shaking his head and vainly endeavoring to free his jaws of this muzzle, a minute or two elapsed, during which he seemed to suffer some discomfort, when suddenly his mouth opened widely, and out crawled Natrix, apparently none the worse for this temporary entombment.  He had turned round when two or three feet from daylight, and come back to see the world once more.  But it so happened that Ophio closed his jaws in time over the few inches of tail which still remained between them.  Nor did he once relax his grasp of this, but quickly and patiently began to work his way up to the head and recommence his meal, and this time with better success.  An hour and a quarter I watched, nor was any evidence of poison seen, so as to reduce the powers of the bitten snake; for bitten it must have been in those prolonged and forcible grasps.

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In these conflicts one could but observe a dogged stupidity on the part of the venomous snake, who, had he but brought coils to his aid, might have simplified matters so easily.  The little Heterodons, and even the Lacertines, often assist themselves with coils in managing their prey, though not themselves constrictors; but the venomous ones have not the slightest notion of helping themselves in this way, as if confident that in time their venom would do its work.

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WHAT WORMS DO

(FROM THE FORMATION OF VEGETABLE MOULD.)

BY CHARLES DARWIN.

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We now come to treat of a curious and important subject,—­namely, the amount of earth which is brought up by worms from beneath the surface, and is afterwards spread out more or less completely by the rain and wind.  The amount can be judged of by two methods,—­by the rate at which objects left on the surface are buried, and more accurately by weighing the quantity brought up within a given time.  We will begin with the first method, as it was first followed.

Near Maer Hall in Staffordshire, quick-lime had been spread, about the year 1827, thickly over a field of good pasture-land, which had not since been ploughed.  Some square holes were dug in this field in the beginning of October, 1837, and the sections showed a layer of turf, formed by the matted roots of the grasses, 1/2 inch in thickness, beneath which, at a depth of 21/2 inches (or 3 inches from the surface), a layer of the lime in powder or in small lumps could be distinctly seen running all round the vertical sides of the holes.  The soil beneath the layer of lime was either gravelly or of a coarse sandy nature, and differed considerably in appearance from the overlying dark-coloured fine mould.  Coal-cinders had been spread over a part of this same field either in the year 1833 or 1834;