the whole interior of the burrow or passage thus made, so that the worm can travel to and fro in it without impediment; while the fact that the slime is continually poured forth afresh prevents the least atom of earth from adhering to its body. This you have doubtless observed, or may observe in a moment, if you will take the trouble to thrust a spade into the ground and give it two or three shakes. You will presently see on all sides the alarmed earthworms coming swiftly to the surface, and will notice how perfectly sleek and clean they are. But these contrivances are only accessories: we have not yet discovered the secret of the easy movement. The mere elongation of the snout is no explanation of the disappearance of the worm in the burrow; for you will naturally and reasonably say that this elongation cannot extend beyond a certain limit; and what then? No further progress can be made unless the hinder parts of the body are, by contraction, drawn up towards the elongated front,but what holds the front in place meanwhile? Why, when the muscles contract, does not the taper wedge-like muzzle slip back and lose the ground it had gained? This we will now look at. I take up this worm and put it in a narrow glass cell, where we may watch its movements. It presently begins to elongate and contract its body vigorously, apparently alarmed at its unwonted position; and the mucus is thrown off in copious abundance. We apply a low microscopic power to it, and catch glimpses, now and again, as it writhes about, of a number of tiny points protruded and retracted with rhythmical symmetry through the skin. Its mobility precludes our discerning much more than that these points are very numerous, that they are arranged in four longitudinal lines, running along the ventral side of the animal,-two lines on each side,—and that in each line there is a point protruded from each of the many rings of which the worm's body is made up. In order to see a little more of these organs we must sacrifice a worm; having killed it, and divided the body in the middle, I cut off, with sharp scissors, a small transverse portion, say two or three rings, and press the fragment between plates of glass. Now, with a higher magnifying power, we discern in the midst of the translucent flesh the points in question. They are not, however, single; but each protrusile organ consists of a pair of transparent, brittle, glassy rods, shaped like an italic s, of which the recurved lines are directed backwards when thrust out from the skin. The mode in which these assist the progression of the worm is well described by Professor Rymer Jones :-" The attenuated rings in the neighbourhood of the mouth are first insinuated between the particles of the earth, which, from their conical shape, they penetrate like a sharp wedge; in this position they are firmly retained by numerous recurved spines appended to the different segments; the hinder parts of the body are then drawn forward by a longitudinal contraction of the whole animal - a movement which not only prepares the creature for advancing further into the soil, but by swelling out the anterior segments forcibly dilates the passage into which the head had been already thrust the spines upon the hinder rings then take a firm hold upon the sides of the hole thus formed; and, preventing any retrograde movement, the head is again forced forward through the yielding mould; so that, by a repetition of the process, the animal is able to advance with the greatest apparent ease through substances which it would at first seem utterly impossible for so helpless a being to penetrate." Gosse. VIVISECTION, OR THE DIVIDED LIFE. A BROWN lizard, nearly five inches in length, startled by our approach, ran hurriedly across the path; and our guide, possessed by the general Highland belief that the creature is poisonous, and injures cattle, struck at it with a switch, and cut it in two immediately behind the hinder legs. The upper half, containing all that anatomists regard as the vitals, heart, brain, and viscera, all the main nerves, and all the larger arteries, lay stunned by the blow, as if dead; nor did it manifest any signs of vitality so long as we remained beside it; whereas the lower half, as if the whole life of the animal had retired into it, continued dancing upon the moss for a full minute after, like a young eel scooped out of some stream and thrown upon the bank, and then lay wriggling. There are few things more curious in the province of the naturalist than the phenomenon of what may be termed divided life vitality broken into two, and yet continuing to exist as vitality in both the dissevered pieces. We see in the nobler animals mere glimpses of the phenomena mere indications of it, doubtfully apparent for at most a few minutes. The blood drawn from the human arm by the lancet continues to live in the cup until it has cooled and begun to coagulate; and when head and body have parted company under the guillotine, both exhibit for a brief space such unequivocal signs of life, that the question arose in France during the horrors of the Revolution, whether there might not be some glimmering of consciousness attendant at the same time on the fearfully opening and shutting eyes and mouth of the one, and the beating heart and jerking neck of the other. The lower we descend in the scale of being, the more striking the instances which we receive of this divisibility of the vital principle. I have seen the two halves of the heart of a ray* pulsating for a full quarter of * The type of the "radiata." See Table, p. 463. an hour after they had been separated from the body and from each other. The blood circulates in the hind leg of a frog for many minutes after the removal of the heart, which meanwhile keeps up an independent motion of its own. Vitality can be so divided in the earth-worm, that each of the severed parts carries life enough away to set it up as an independent animal; while the polypus, a creature of still more imperfect organisation, and with the vivacious principle more equally diffused over it, may be multiplied by its pieces nearly as readily as a gooseberry bush by its slips. It was sufficiently curious, however, to see, in the case of this brown lizard, the least vital half of the creature so much more vivacious, apparently, than the half which contained the heart and brain. It is not improbable, however, that the presence of these organs had only the effect of rendering the upper portion, which contained them, more capable of being thrown into a state of insensibility. A blow dealt on the head of one of the vertebrata at once renders it insensible. It is after this mode the fisherman kills the salmon captured in his weir, and a single blow, when well directed, is always sufficient, but no single blow has the same effect on the earth-worm; and here it was vitality in the inferior portion of the reptile- the earthworm portion of it, if I may so speak that refused to participate in the state of syncope into which the vitality of the brain seems to impart to the whole system in connexion with it an aptitude for dying suddenly, a susceptibility of instant death, which would be wanting without it. The heart of the rabbit continues to beat regularly long after the brain has been removed by careful excision, if respiration be artificially kept up; but if, instead of amputating the head, the brain be crushed in its place by a sudden blow of a hammer, the heart ceases its motion at once. And such seemed to be the principle illustrated here. But why the agonised dancing on the sward of the inferior part of the reptile? Why its after painful writhing and wriggling? - The young eel scooped from the stream, whose motions it resembled, is impressed by terror and can feel pain; was it also impressed by terror or susceptibility of suffering? We see in the case of both exactly the same signs, the dancing, the writhing, the wriggling; but are we to interpret them after the same manner? In the small red-headed earthworm divided by Spalanzani, that in three months got upper extremities to its lower part, and lower extremities in as many weeks to its upper part, the divided blow must have dealt duplicate feelings- pain and terror to the portion below, and pain and terror to the portion above — so far, at least, as a creature so low in the scale was susceptible of these feelings; but are we to hold that the leaping, wriggling tail of the reptile possessed in any degree a similar susceptibility? I can propound the riddle, but who shall solve it? H. Miller. THE MODE OF PROPAGATION OF THE SYLLIS, Ir was formerly believed, in accordance with the observations of the old Danish zoologist, Müller, that these little errant annelids, which are only from two to three inches long, were fissiparous; that is to say, that one individual being first single and entire, could separate into two halves, each of which acquiring rapidly either a head or a tail, became a perfect animal, destined to live precisely in the same manner as the original being from which it had sprung. This mode of generation, which is common enough in simple animals, was very remarkable in the case of the genus Syllis, in which the organisation is of a somewhat complicated kind. It must be remembered, however, that very different conditions prevail among the animals of this genus. When a syllis is about to reproduce itself, a number of |