irregular, foliated pattern, over which the usual film of the sponge is laid during life.*

* Bryce M. Wright in "The American Naturalist."

At one time this sponge was so rare that specimens fetched enormous prices; now, by the progress of commerce, it has become more common, and specimens of great beauty may be had for a few shillings.

CHAPTER V.

OILS FROM MARINE MAMMALS.

The seal fishery-Seal oil-Yield of oil from blubber-Seal-skins-The fur seal-The walrus-The whale fishery-Imports of train oil or blubber, spermaceti, and whalebone-Porpoise oil-Dugong oil.

Oils from the Mammals.-One of the articles contributed by marine animals to the wants of industry is oil, which is largely obtained both from mammals and fishes. The aggregate value of the trade in these in the United Kingdom alone exceeds £1,000,000 sterling a year. Some of these oleaginous substances are employed as food by man, some in manufactures, and others in medicine.

Oil for commercial purposes is obtained in greater or less quantities from numerous inhabitants of the seas— from the marine mammals, the right and spermaceti whale, the seal, sea-elephant, dugong, porpoise, etc.; from the shark, sunfish, cod, herring, and numerous small fish, which are especially sought for the oil they yield.

The great trade in animal oils and fatty substances indicates the care with which oily matters, rich in carbon and hydrogen, are sought in all countries, supplying as they do a great number of wants in countries the most civilized, as well as among people still in their primitive state. We know that fish oils are beneficial in consumptive cases, as

with cod-liver oil and that obtained from the dugong; but they might be often used with advantage for inunction, where they are not easily retained on the stomach.

Dr. T. Thompson has pointed out the medicinal value of various animal oils besides cod-liver oil, such as sperm and seal oil; and the result of his observations was a conviction that fish oils generally resembled one another in their remedial properties, although differing in their aptitude for digestive assimilation in the human stomach. He tried neat's-foot oil, an animal oil obtained from a soft, solid fat found between the parchment and the leather skin of animals; also shark-liver oil, and an oil obtained from a species of fish abounding on the Malabar coast; and these trials were frequently attended with encouraging results.

The practice of daily inunction is common in many warm countries, and serves to soften the skin and keep the body in health. In tropical regions, vegetable oils are chiefly used; but the New Zealanders and some others use shark oil. The Esquimaux and Greenlanders imbibe large quantities of train, seal, and various fish oils; whilst the natives about the large rivers and coasts of Brazil use turtle oil, and fat obtained from the alligator and crocodile. The natives of many parts of India use shark oil and that from the liver of the sword-fish in anointing their skin.

Those who are employed in the woollen trade, and in soap, candle, and other factories, where oil and fats are largely used, enjoy a comparative immunity from scrofula and phthisis. Sailors believe a whaling voyage to be a cure for consumption; and probably the quantity of oil drunk and taken into the skin may have its beneficial effect upon the system.

The Seal Fishery.-After the cod fishery, the seal fishery is the most profitable branch of trade in New

foundland. More than 350 vessels are engaged in it. The seals whelp their young in January and February on the ice field of Labrador; this ice is floated southwards by the ocean currents, and is always to be found on the coast of Newfoundland after the middle of March. The take of seals varies; in some years the export of skins being under 200,000, in others exceeding 450,000. The value of the seal oil shipped ranges from £160,000 to £200,000. The yield of oil is about 11 gallons from one cwt. of blubber.

Seal oil and cod oil are now two of the most important, whale oil having much declined in quantity, owing to the fishery being less earnestly prosecuted; but there are very many fish oils, extracted in different quarters, which have a local and general use, such as shark oil, herring oil, menhaden oil, etc.

Seal Oil.-There are three classifications of seal oil: that which drains spontaneously by the pressure of the layers of the skins one over the other; that which is prepared by submitting the fat to the action of steam in hermetically closed boilers; and that which is obtained from the residual mass, submitted to a high pressure.