Zoology for High Schools and Colleges

H. Holt, 1880 - 719 páginas

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Página 593 - It must not be overlooked, however, that there is a very striking difference in absolute mass and weight between the lowest human brain and that of the highest ape...
Página 199 - Phoronis, Echinus, etc. The first point of difference from other animals in the development of .all vertebrates is seen in the formation of the dorsal ridges and their closing to form a nerve-canal. This mode of formation of the nervous system is characteristic of the vertebrates alone, except the Ascidians. Another primary character allying the Ascidians to the vertebrates, is the presence of a chorda dorsalis, first seen in the adult Appendicularia by J.
Página 547 - His fur has so much the hue of the moss which grows on the branches of the trees, that it is very difficult to make him out when he is at rest.
Página 289 - ... sea water, in which the embryo revolves. At a little later period the embryo throws off an embryonal skin, the thin pellicle floating about in the egg. Still later in the life of the embryo the claws are developed, an additional rudimentary gill appears, and the abdomen grows broader and larger, with the segments more distinct; the heart also appears, being a pale streak along the middle of the back extending from the front edge of the cephalothorax to the base of the abdomen.
Página 337 - ... by rubbing together the upper surface of the front edge of the wings and the under surface of the wing-covers.
Página 307 - ... pass through the fine coatings of the digestive canal by osmosis, and mingle outside of this canal with the currents of blood which pass along the ventral and lateral parts of the body. Into the pyloric end of the stomach empty the urinary tubes, their secretions passing into the intestine. These organs are exclusively depuratory and urinary, relieving the body of the waste products.
Página 545 - I have seen them stick fast thereto, when they have been no bigger than a small raspberry, and seemingly inanimate. She has a paunch or false belly, wherein she carries her young, after they are from those teats, till they can shift for themselves. Their food is roots, poultry, or wild fruits. They have no hair on their tails, but a sort of a scale, or hard crust, as the beavers have.
Página 149 - Cysticerci,' says Dr Cobbold, 'may develop themselves in almost any situation in the human body, but they occur most frequently in the subcutaneous, areolar, and intermuscular connective tissue ; next, most commonly in the brain and eye, and lastly, in the substance of the heart and other viscera of the trunk.
Página 80 - Could we raise one of these coral-bound islands from the waves, we should find that the reefs stand upon submarine slopes, like massy structures of artificial masonry; some forming a broad flat platform or shelf ranging around the land, and others encircling it like vast ramparts, perhaps a hundred miles or more in circuit.

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