SHOWING PRINCIPLE OF VENTURI.
Ex.—S V is the sub-clavian vein; J is the jugular vein; D is the thoracic duct, through which the chyle is poured into the blood.
THE TRADES AMONG ANIMALS.
An ancient saying declares that “Poets are born, not made,” and classic story informs us that Minerva sprang full armed from the head of Jove. Something like this natural perfection appears in the occupations of the lower orders of creation. Man is a creature of education, absolutely unlimited in point of time in the possibilities of his development. Other animals, within their own limited scope often attain an excellence superior to his. Note the scent of the greyhound, the hearing of the cat, the sight of the eagle. As artisans they have few apprentices, though it must be confessed that some are better workmen than others, and they are not without “bosses.” Observe a few of their trades. The brant-goose is a navigator, which may have already found the pole. The heron is a fisherman, who carries his torch upon his breast. Swallows are excellent masons; so are wasps and the caddis fly.
There is a spider that is a diver; he makes his own bell and fills it with air. The bee is a geometrician that never studied Euclid. The ant is a political economist, who, like Joseph, lays up supplies for a time of want. There is a “tailor bird.” There are hosts of hunters among the carnivora. The nautilus is a “little sailor,” and weavers are innumerable. Beavers unite the trades of lumbermen and civil engineers. There are carpenters and paper makers, indeed, time would fail in the attempt to mention all the occupations pursued in this busy world of animate creation. Yet over all these the Almighty has given man dominion. They are but organisms impelled to their appointed tasks by unreasoning instinct, but, as Sir William Hamilton has said: “Man is not an organism, but an intelligence served by organs.”
A BIRD’S HEAD.
Ex.—The mandibles form a pair of scissors. The tongue is a spear.
Note.—Through the courtesy of Messrs. Ivison, Blakeman, Taylor & Co., of New York, the cuts in this article are taken from two of their excellent publications, Gray’s “Lessons and Manual of Botany,” and Hitchcock’s “Anatomy and Physiology.”