Animal Studies: A Text-book of Elementary Zoology for Use in High Schools and CollegesD. Appleton, 1903 - 459 páginas |
No interior do livro
Resultados 1-5 de 60
Página 14
... similar parts being de- rived from a common ancestral stock . It is sometimes said that the inside of an animal tells what it is , the out- side where it has been . In the internal struc- ture , ancestral traits are perpetuated with ...
... similar parts being de- rived from a common ancestral stock . It is sometimes said that the inside of an animal tells what it is , the out- side where it has been . In the internal struc- ture , ancestral traits are perpetuated with ...
Página 23
... Similar projections at the opposite end of the cell are withdrawn , and their substance may flow into the newly formed lobe , which gradually swells in size and pushes forward . Thus , by constantly advancing the front part of the body ...
... Similar projections at the opposite end of the cell are withdrawn , and their substance may flow into the newly formed lobe , which gradually swells in size and pushes forward . Thus , by constantly advancing the front part of the body ...
Página 24
... similar portions , and very soon afterward the rest of the body separates into two independent masses of equal size ( Fig . 7 , D ) , each of which , when entirely free , contains a nucleus . In this way two daughter amabæ are formed ...
... similar portions , and very soon afterward the rest of the body separates into two independent masses of equal size ( Fig . 7 , D ) , each of which , when entirely free , contains a nucleus . In this way two daughter amabæ are formed ...
Página 25
... similar envelopes of lime or flint , and still others , as they continue to grow , build on additional chambers , giving rise to a great variety of forms often of wonderful beauty . In the tropics , particularly , some of the shelled ...
... similar envelopes of lime or flint , and still others , as they continue to grow , build on additional chambers , giving rise to a great variety of forms often of wonderful beauty . In the tropics , particularly , some of the shelled ...
Página 35
... similar to Volvox , and at this point the young larva leaves the parent . The next transformation consists in a pushing in of one side of the sphere , just as one might press in the side of a hollow rubber ball . The depression ...
... similar to Volvox , and at this point the young larva leaves the parent . The next transformation consists in a pushing in of one side of the sphere , just as one might press in the side of a hollow rubber ball . The depression ...
Outras edições - Ver tudo
Palavras e frases frequentes
abundant adapted adult Amaba amphibians animals annelids ants appearance Arthropods attached bear become bees birds body brain burrow butterfly called canal cavity cells chitin clams color common crabs crayfishes crinoids Crustacea digestive dorsal earthworm eggs enemies exist external eyes feed feet female fins fishes flagellum flatworms forms fossils fresh-water frogs gastrula gills habits hatched head highly individuals insects instinct intestine jelly-fish known lancelet larva larvæ legs less limbs live lizards male mals mammals matter mollusks mouth muscles natural nerve nest notochord organs oxygen pair parasites parent plants possess prey protective resemblance Protozoa pupa regions relatively reptiles rocks Sacculina salamanders sand segments shell side skeleton skin smell snails snakes special sense species spines sponge squirrel stage starfishes stomach structure substance surface surroundings swimming tail teeth tentacles tion tree usually various vertebrates wings workers worms young
Passagens conhecidas
Página 280 - There is no exception to the rule that every organic being naturally increases at so high a rate, that, if not destroyed, the earth would soon be covered by the progeny of a single pair. Even slow-breeding man has doubled in twenty-five years, and at this rate, in less than a thousand years, there would literally not be standing room for his progeny.
Página 209 - Its summer plumage so exactly harmonizes with the lichen-coloured stones among which it delights to sit, that a person may walk through a flock of them without seeing a single bird; while in winter its white plumage is an almost equal protection.
Página 360 - He cannot be mistaken for any other, and his flaming vest and blue stockings show that he does not court concealment. He is very abundant in the damp woods, and I was convinced he was uneatable so soon as I made his acquaintance and saw the happy sense of security with which he hopped about. I took a few specimens home with me, and tried my fowls and ducks with them ; but none would touch them. At last, by throwing down pieces of meat, for which there was a great competition amongst them, I managed...
Página 408 - Mono had never seen an egg, but his inherited impulses bore a direct relation to feeding on eggs, just as the heredity of Macacus taught the others how to crack nuts or to peel fruit. To each of these monkeys we gave an egg, the first that any of them had ever seen. The baby monkey, Mono, being of an egg-eating race, devoured his egg by the operation of instinct or inherited habit. On being given the egg for the first time, he cracked it with Iris upper teeth, making a hole in it, and sucked out...
Página 359 - In the woods around Santo Domingo there are many frogs. Some are green or brown, and imitate green or dead leaves, and live amongst foliage. Others are dull earth-coloured, and hide in holes and under logs.
Página 281 - The elephant is reckoned the slowest breeder of all known animals, and I have taken some pains to estimate its probable minimum rate of natural increase; it will be safest to assume that it begins breeding when thirty years old, and goes on breeding till ninety years old, bringing forth six young in the interval, and surviving till one hundred years old ; if this be so, after a period of from 740 to 750 years there would be nearly nineteen million elephants alive, descended from the first pair.
Página 192 - Pipidce, or Surinam Toads, there are rarely teeth, and the mouth is destitute of a tongue. A singular and hideous species (Pipa Americana) is the best known, and it inhabits Brazil and Surinam. In this curious Amphibian the eggs are placed by the male on the back of the female, in the integument of which, in cell-like cavities, the eggs are hatched and the young developed.
Página 318 - ... and varied businesses ; and of the tireless persistence of the workers until they fall exhausted and dying in the performance of their duties. The community, it is important to note, is a persistent or continuous one. The workers do not live long, the spring broods usually not over two or three months, and the fall broods not more than six or eight months ; but new ones are hatching while the old ones are dying, and the community as a whole always persists. The queen may live several years, perhaps...
Página 316 - Finally, a small mass of food is put into the cell, and the cell is 'capped' or covered with wax. Each larva, after eating all its food, in two or three days more changes into a pupa, which lies quiescent without eating for thirteen days, when it changes into a full-grown bee. The new bee breaks open the cap of the cell with its jaws and comes out into the hive, ready to take up its share of the work for the community. "In a few cases, however, the life history is different. The nurses...