Animal Life: A First Book of ZoölogyD. Appleton, 1900 - Всего страниц: 329 |
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Стр. 4
... spots which appear to be granules are simply cross sections of fine threads of dense protoplasm which lie coiled and tangled in the thinner , clearer protoplasm . And , finally , 3. What the primitive cell can do . - The 4 ANIMAL LIFE.
... spots which appear to be granules are simply cross sections of fine threads of dense protoplasm which lie coiled and tangled in the thinner , clearer protoplasm . And , finally , 3. What the primitive cell can do . - The 4 ANIMAL LIFE.
Стр. 9
... finally divides in two . 5. Paramecium . - Another protozoan which is common in stagnant pools and can be readily obtained and observed is Paramecium ( Fig . 5 ) . The body of the Paramecium is much larger than that of the Amaba , being ...
... finally divides in two . 5. Paramecium . - Another protozoan which is common in stagnant pools and can be readily obtained and observed is Paramecium ( Fig . 5 ) . The body of the Paramecium is much larger than that of the Amaba , being ...
Стр. 13
... Finally it settles down and develops a stalk . Vorti- cella shows two kinds of fission - one the usual division into equal parts , and another division into unequal parts . In this latter kind , called reproduction or multiplication by ...
... Finally it settles down and develops a stalk . Vorti- cella shows two kinds of fission - one the usual division into equal parts , and another division into unequal parts . In this latter kind , called reproduction or multiplication by ...
Стр. 30
... finally die . They take absolutely no part in reproducing the colony . One of the minute free - swim- ming cells fuses with one of the enormous egg cells , the new cell thus formed being a resting spore . From this resting spore a new ...
... finally die . They take absolutely no part in reproducing the colony . One of the minute free - swim- ming cells fuses with one of the enormous egg cells , the new cell thus formed being a resting spore . From this resting spore a new ...
Стр. 35
... finally escapes from the body of the parent sponge , and lives for a short time as an active free - swimming animal . Its body consists of an oval mass of cells , of which those on one side are provided with cilia or swimming hairs ...
... finally escapes from the body of the parent sponge , and lives for a short time as an active free - swimming animal . Its body consists of an oval mass of cells , of which those on one side are provided with cilia or swimming hairs ...
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adaptation adult alimentary canal Amaba ants artificial selection becomes bees beetles birds body wall breathing butterfly called cavity chitin CLASS colony color complex animals composed conjugation crab differentiation digestion divide division of labor ectoderm egg cells embryo existence feed female fertilized fish flagella free-swimming function gastrula Globigerinæ habits hatched higher animals honey-bee Hydra inclosed increase insects instinct intestine jelly-fishes kinds of animals larva larvæ layer live male mals mammals many-celled animals mass medusæ metamorphosis naturalists nerve nest nucleus ocean one-celled organs outer oxygen Pandorina papillæ Paramecium parasites parent perform plant-lice plants polyp prey primitive processes produced protoplasm Protozoa pseudopods pupa queen Radiolaria reproductive cells Sacculina sea-anemone shell simple simplest animals single cell special sense species sperm cells spherical sponge stage structure substance surface swimming tentacles tion tissues vertebrates Volvox Vorticella wings workers worms young
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Стр. 115 - 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.
Стр. 215 - 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...
Стр. 20 - ... inhabitants of the water has followed a roundabout path from the surface to the bottom and then back into the water. When this fact is seen in all its bearings and its full significance is grasped, it is certainly one of the most notable and instructive features of evolution. The food-supply of marine animals consists of a few species of microscopic organisms which are inexhaustible and the only source of food for all the inhabitants of the ocean.
Стр. 116 - 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.