foot, keeping the left suspended behind, with its toe closely pointed to the heel of the right. As he advances, the left must be brought past the inside of the right with a slight jerk; this slight jerk produces an opposing balancing motion of the body; the right foot then quickly presses, first on the outside of its heel, and then on the inside of its toe, and by placing the left foot down before it, and striking outside to the left, giving at the same time a slight push with the inside of the right toe, he passes from right to left. Having learned this much, the skater will proceed to change from left to right, and then from right to left again, without any trouble.

To skate outside edge properly, the toe of the suspended foot must be pointed close to the ice behind the other, and kept there until this foot be required, when it must be brought sharply round to the change. The skater must keep himself erect, leaning most on the heel. This mode of skating being acquired, there is an endless variety of figures and modes of movement that may be produced, some of which are known by the names of "the Dutch travelling roll," "the spread eagle," "the mercurial figure," "the backward outside edge," "the circle," "the figure of 8," "the figure of 3," "walking," "the minuet," "the pirouette," "the quadrille," "warming and screwing," &c.

The exercise of skating is a healthy and pleasant one. At the present moment (December the 8th) there does not appear much chance of frost; but as Peter Parley is sometimes weather-wise, he prognosticates that before this day month there will be both skating and sliding in plenty.—When the cold does come do not forget the houseless wanderer.

HAT is sponge? Is it an animal or vegetable? Some say it is an animal; some declare positively, as many ignorant persons often declare, that it is a vegetable. The ancients admitted that sponges were endowed with sensation, because they seemed to avoid the hand that would touch them, and appeared to resist the efforts that were made to remove them from their submarine dwelling. They supposed sponges to hold an intermediate rank between animals and vegetables. In the present improved state of natural history, sponges are regarded as zoophytes; they occupy the lowest station in the scale of organization, and the name porifera has been assigned to them.

The tribes of porifera which form the various species of sponge, are found in great abundance on every rocky coast of the ocean from

the shores of Greenland to those of Australia. They attain a larger growth within the tropics, and are found to be of a smaller size but firmer texture as we approach the polar circles. They occur as well in places covered perpetually by the sea as in those which are left dry at every recess of the tide. They adhere to and spread over the surface of rocks and marine animals, and cling so firmly as not to be removed without laceration and injury to their bodies. Although they thrive best in sheltered cavities of rocks, they also come to maturity in situations exposed to the unbroken foam of the surge. They cover the nakedness of cliffs and boulders, they line with a variegated and downy fleece the walls of submarine cones, or hang in living stalactites from the roof.

The external appearance of sponges approaches that of plants, but the internal organization is altogether different from any known vegetable. They are composed of a soft flesh intermingled with a tissue of fibres, some solid, others tubular, and the whole interwoven into a curiously complicated net work. The solid portion, or basis of the sponge, composed partly of a horny and partly of a flinty or chalky matter, is called the axis of the zoophyte; as it seems to support the softer substance of the animal, it may be said to perform the office of the skeleton in the higher orders of animals by giving form and protection to the entire fabric.

The fleshy portion of the sponge is of so tender and gelatinous a nature and is so much injured by the slightest pressure, that the fluid parts escape and the whole soon melts away into a thin oily liquid. The soft flesh, as seen by the microscope, appears to contain a number of minute grains surrounded by transparent jelly. The surface of every part of a living sponge presents to the eye two kinds of orifices,

the larger having a rounded shape and a scaly raised margin which form projecting nipples; the smaller being far more numerous and very minute, constituting what are usually called the pores of the sponge.

It is to the superficial, liquid, gelatinous substance that naturalists so long assigned sensibility, and a contractile power, which occasioned it to shrink from the touch. The round apertures visible on the surface of sponges were also supposed to dilate and contract, so as to establish numerous currents of water, whereby the function of nutrition was supposed to be served; but modern researches clearly prove that the sponge does not possess, in any sensible degree, that power of contraction which has for so many ages been ascribed to it. The round apertures in the surface of the living sponge seem to be destined for the discharge of a constant stream of water from the interior of the body, carrying away particles which separate from the sides of the canal. For the supply of these constant streams, a large quantity of water enters into the body of the sponge by myriads of pores, which exist in every part of the surface, and this water conveys materials necessary to the support of the animal. The pores convey the fluid into the interior, where, after filtering through the numerous channels which pervade the whole substance, it is collected into wider passages and finally discharged. The means by which the animal produces these currents and extracts nutrition from them are entirely unknown; they are, most probably, occasioned by some internal movement.

The structure of sponges is as regular and determinate and presents as systematic arrangements of parts as that of any other animal. In some species, as in the common sponges, the basis is horny and elastic,

consisting of cylindrical tubes which mutually communicate and form continuous canals throughout the whole mass. Others have a kind of skeleton, composed of a tissue of needle-shaped crystals of chalk or of flint, disposed around the internal canals of the sponge, so as to protect them from compression and from the entrance of noxious substances.

Although, in common with zoophytes in general, sponges are permanently attached to rocks and other solid bodies in the ocean, yet, in the earlier stages of their growth, they are endowed with considerable powers of locomotion. The means employed in the general economy of nature for the multiplication and diminution of each race of beings are calculated to excite our admiration and gratitude. The parent plant scatters its seeds around, where they take root in the adjacent soil, or they are borne by the winds and the waters to less populous localities. In animals which are endowed with a wide range of activity, the young are at first helpless, and require all the fostering care of the parent, unless, as in the case of some oviparous tribes, a store of nutriment is provided for the young one in the egg, where it remains until it has acquired locomotive powers to enable it to go in search of food. In sponges, the parent remains fixed to one spot, and sends forth its young to seek a proper habitation; and they having done so, remains fixed during the remainder of their existence.