Page:Popular Science Monthly Volume 3.djvu/540

This page has been validated.

524

THE POPULAR SCIENCE MONTHLY.

dred putrefying corpses at a time to certain holy places, often distant thirty or forty days' travel.

Sponges.—Naturalists are now generally agreed in classing the sponge with animals, but place it in the very lowest rank of the Protozoa, abutting on the vegetable kingdom. Like a plant, the sponge grows on rocks or other substances in water, being often found attached to the shells of living crustaceans. It consists of a gelatinous substance called sarcode, and of a framework made up of horny, elastic fibres (keratose), or of calcareous or siliceous spicules. The keratose is the sponge of commerce, and its value depends upon the elasticity and compressibility of its fibres.

The sarcode is sometimes represented to be an amorphous mass of glairy substance, but accurate observation with the microscope shows, according to Huxley, that it is constituted as follows: There is, first, an external layer, continuous, and made up of an aggregation of organisms with nuclei, and much resembling amoebae. This stratum is separated from another of identical structure by a chamber filled with water. The outermost layer has a multitude of pores, through which the supply of food and oxygen enters. The floor of the lower and thicker layer has a number of orifices opening into tubes which widen out into globular caverns a little below the surface. The sides of these globules are studded with amoeba-like organisms, each having a cilium, or appendage resembling an eyelash, which is constantly vibrating, and so establishing a current in a direction downward into canals which open into great, funnel-like, or crater-like orifices. These great orifices are the exhalant apertures, the pores inhalant apertures. The food and oxygen in the stream of water is appropriated by the sponge-organisms individually as it flows by.

When placed under the microscope, the living sponge is a wonderful sight. Dr. R. E. Grant, who was the first to witness it, having put a small branch of living sponge, with some sea-water, into a watch-glass, saw a "living fountain vomiting forth from a circular . cavity an impetuous torrent of liquid matter, and hurling along, in rapid succession, opaque masses, which it strewed everywhere around." Here is a circulation of water answering the same purpose as that of blood in other animals. The sponge takes in food and oxygen through its minute pores, and voids the waste matter through the oscula, or larger orifices. In the Spongia fluviatilis, or fresh - water sponge, the pores are not permanent, but they appear and disappear without leaving a trace behind, as in the case of the amœbæ.

The spiculæ of the siliceous sponges assume sundry shapes, being sometimes straight, like needles; again headed and pointed like pins, or furnished with grapnel-like hooks at their ends, etc. Perhaps the most curious of all the sponges is the "glass-rope" (Hyalonema), which has the appearance of a rope of twisted glass fibres, with a fibrous sponge attached to one end. Another very interesting form of sponge is the Eupledella speciosa, or Venus's flower-basket, which grows in the shape of a cornucopia, and is composed of fine glossy threads of silica.

The best sponges for toilet use come from the Ægean, and are found in about eight fathoms of water. They are gathered by divers. A coarse quality of sponge is found on the coasts of Florida and the West Indies. These are gathered with long-hafted forks. To remove the sarcode, the sponge is buried for some days in the sand, until the animal matter rots, and then the horny keratose is soaked and washed.

Jute-Paper.—One day's issue of the Dundee (Scotland) Advertiser was recently printed on paper made of jute. The material is said to be of good, firm quality, though thin and transparent, and of a yellowish tinge. The chief objection hitherto urged against jute-paper is its dark color; and, if, as appears probable, this can be obviated, there is no doubt that jute-paper will quickly supersede that made from rags, except for the best qualities. The jute employed in this instance is old bagging, which commands but a low price. As an encouragement to inventors, the proprietors of the Advertiser offer a premium of £50 for the best ream of paper made entirely from jute, of the size and weight of the paper on which the