SPONGES. Mediterranean civilisation has used sponges from the earliest times. Homer describes Hephaestus as washing off the grime of the smithy with a sponge (Iliad, xviii., 414), while the household servants of Penelope and Odysseus used sponges to swab down the tables in the dining-hall (Odyssey i., III; xxii., 22, 439). Aristotle calls the kind of sponge used for padding helmets and greaves Achilleion, and says it was "very fine, very dense, and very strong"; this was probably the "Elephant's Ear" sponge. The Romans made paint-brushes of "Achilleum" (Pliny), and used sponges on wooden handles for mops. The Gospels (Mark xv., 36) show that a sponge was a common article in Roman Jerusalem.
Commercial Sponges.—Modern trade recognises five princi pal kinds of sponges from the Mediterranean—(I) The Fine Tur key Cup (Euspongia officinalis mollissima), is softest and most delicate, but little more so than (2) the Fine Turkey Solid (E. officinalis adriatica), the soft bath-sponge, cushion-shaped and larger than the cup-sponge. (3) The Zimocca, Brown Tur key or Hard Greek sponge—"fine dure" of the French—(Euspon gia zirnocca) is a hard sponge, usually a cup-shape flattened almost to a disc; its harsh surface makes it useful for scrubbing. (4) The Elephant's Ear (Eu spongia officinalzs lamella) is a thin-walled shallow cup whose shape and elasticity gives it spe cial value for stuffing, its texture and flatness for polishing. (5) The Honeycomb (Hippospongia equina) is the well-known Medi terranean bath-sponge (French "Venise") ; its large size, uniform fibre, and many wide cavities dis tinguish it from the Turkey Solid, while the comparatively con tinuous skin between the round holes on the upper surface dis tinguishes it from the bath-sponges now obtained from the west Atlantic.
In sponges from the shallow seas near the Bahamas and Florida the round holes are usually each bordered by a pronounced circular ridge or fringe; often each is on the top of a "tower" or finger (noticeably in the Reef Sponge or (6) Glove Sponge, Euspongia tubulifera) ; possibly this protection of the vent-hole is because there is more sediment in the water. It may be for the same reason that we find in this American sea no cup-sponges or toadstool shapes. The fibre is more brittle than in sponges from
Levantine waters, possibly because of suspended lime in the water; but it must also be remembered that the water-temperature at the Bahamas is about 27° C. against 17° C. in the Mediterra nean. Compared with the Mediterranean, the Caribbean sponges show more numerous tassels and brushes on the upper surface, especially in (7) the Wool Sponge (Hippospongia gossypina), with surface resembling a lamb's fleece, the staple "bath-sponge" of these fisheries. The surface is characterized by grooves and deep channels between the tufts, because the skin in life has less, or less resistant, skeleton than in the Mediterranean; consequently water-passages which were in life roofed with skin are open it the cleaned skeleton, the tufts being the columns which supported the skin. (8) The Velvet Sponge (Hippospongia maeandriformis) shows these grooves very markedly; it comes nearest in softness to the Turkey Sponges. (9) The Hard-head or Honeycomb Reef Sponge (Euspongia agaricina) and (to) the hairy Yellow Sponge (Euspongia corlosia) are hard when squeezed, approaching the character of the Zimocca. (I 1) The Grass Sponges (Hippo spongia graminea and H. cerebriformis) are the least valuable commercially; they have the form of a truncated cone fluted with deep furrows. Roughly, one third of a pound's weight of Turkey Cup sells for about as much as a pound of Mediterranean Honey comb or Wool Sponge, as three pounds of Velvet or Yellow Sponge, or as ten pounds of Grass or Glove. The lagoons of Bermuda grow a hard sponge (Hippospongia lapidescens turrita) with kiln-like towers, which is only suitable for rough purposes.
Australian waters have a number of undoubtedly valuable sponges; fine bath-sponges occur in Torres Straits, on the west coast, and near Port Phillip. In the South Caroline Islands they fish and use (12) a fine soft sponge (Coscinoderma lanuginosum) much resembling the Turkey Sponge in character; the same sponge occurs near Port Phillip. The Great Barrier Reef Expedition is at present (October, 1928) re-investigating the Australian toilet sponges and the results seem promising (June 1929).