has a heart composed of only one ventricle and one auricle, breathes by gills, and does not suckle its young. The whale has the very opposite of all these characters: its blood is hot, like that of man, quadrupeds, and birds; it has, like them, a double heart of two ventricles and two auricles; like them it breathes the atmosphere by lungs; and like them, also, it suckles its offspring. There are various kinds of whales; as the cachalot, the broad-nosed whale, the white. whale, the fin-fish, the grampus, porpoise, and several others. Some of them have formidable teeth, are very voracious, and great destroyers of fish and seals; while some are destitute of only on animals of very small great Greenland or common sticetus), and to it I now inny remarks. This species of seventy feet, and an inlo will weigh seventy tons. eth; it has no arms t swallow any bulky barely wide enough , then, does it live? e supported? The ng consists of minute LETTER XV. IN my last letter I referred you to some examples of Divine wisdom displayed in the contrivances and arrangements which are followed in the economy of nature, for adapting animals to that mode of life which they have been allotted to pursue; and as I consider this a most useful kind of study, I will offer you one more example of a similar kind, in a noted inhabitant of the ocean the whale. --- Were our ideas of nature's productions not founded on strict and actual observation and research, we should, instead of possessing that satisfactory knowledge which every day is bringing to light, still wander in those mazes of error and conjecture which always characterise the infancy of science. How long, for instance, was the whale thought to be a fish? and by how many persons is it thought to be such even at the present time? Yet a fish it is not, any further than that it inhabits the water, and is of a fish-like shape. The true fish is cold-blooded, has a heart composed of only one ventricle and one auricle, breathes by gills, and does not The whale has the very op suckle its young. posite of all these characters: its blood is hot, like that of man, quadrupeds, and birds; it has, like them, a double heart of two ventricles and two auricles; like them it breathes the atmosphere by lungs; and like them, also, it suckles its offspring. There are various kinds of whales; as the cachalot, the broad-nosed whale, the white whale, the fin-fish, the grampus, porpoise, and several others. Some of them have formidable teeth, are very voracious, and great destroyers of fish and seals; while some are destitute of teeth, and prey only on animals of very small size. Such is the great Greenland or common whale (Balæna mysticetus), and to it I now intend to confine my remarks. This species grows to the length of seventy feet, and an individual sixty feet long will weigh seventy tons. It has, as I have said, no teeth; it has no arms for seizing its food; it cannot swallow any bulky object, for its œsophagus is barely wide enough to admit a man's arm. How, then, does it live? how is its vast bulk to be supported? The food of this enormous being consists of minute called the northern argonaut (Argonauta arctica), which is less than the third of an inch in diameter; of some little crabs (Cancer pedatus and C. oculatus), and of some equally minute species of the genus Clio. According, however, to Mr. Scoresby's observations, a small kind of shrimp, about half an inch in length, which is semitransparent, and of a pale red colour, constitutes its chief food. In the stomach of a large whale he found these shrimps alone; but I should suppose that the food will vary according to the part of the ocean where the animal may feed; and hence, that as such part may abound in medusæ, or crabs, or shrimps, the nature of the whale's food will vary accordingly. Be this as it may, however, let us enquire how the huge animal contrives to capture a sufficiency of this minute prey. Suppose, then, that you had a large quantity of sea-water containing the shrimps and other species alluded to, what would be the most effectual means which you could employ to separate them from it? Could you adopt any more efficient method than that of passing it through a filter? This plan would let the water run off, and leave them behind; and this is the contrivance which has been adopted in the whale; and what other would have answered the purpose I cannot conjecture. The filter is placed in the mouth, and is of a most perfect kind. With the substance of which it is composed you are well acquainted, though perhaps you have never thought of enquiring into its history. I speak of the elastic substance called whalebone, for it is of it that the filter is made. But before mentioning its structure let me remind you of the great size of the whale's mouth. Mr. Scoresby, whose intelligence and opportunities of observation make him the best of all authorities on this subject, says, that when open, "it presents a cavity as large as a room, and capable of containing a merchant ship's jolly boat full of men, being six or eight feet wide, ten or twelve feet high (in front), and fifteen or sixteen feet long."* The filter, then, is composed of above three hundred spars or blades of whalebone, or as it is now more properly termed, of baleen, fixed in the gum of each side of the upper jaw, and making in all between six and seven hundred. These are all joined firmly by their upper edge to the palate, for there are none attached to the lower jaw. Their broad ends are planted in the gum, and their narrow ends point to the * Account of the Arctic Regions, vol. i. p. 455. |