Animal Life: A First Book of ZoölogyD. Appleton, 1900 - Всего страниц: 329 |
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Стр. 11
... conjugation , began ( Fig . 7 ) . Each Paramecium , with its nuclei com- posed of parts of the nuclei from two distinct individuals , now simply divides in two , and a large number THE LIFE OF THE SIMPLEST ANIMALS 11.
... conjugation , began ( Fig . 7 ) . Each Paramecium , with its nuclei com- posed of parts of the nuclei from two distinct individuals , now simply divides in two , and a large number THE LIFE OF THE SIMPLEST ANIMALS 11.
Стр. 31
... distinct division of labor and an accompanying differentiation of structure . Certain cells of the colony do certain things , and are modified in structure to fit them specially for their particular duties . The steps from the simplest ...
... distinct division of labor and an accompanying differentiation of structure . Certain cells of the colony do certain things , and are modified in structure to fit them specially for their particular duties . The steps from the simplest ...
Стр. 32
... distinct organisms or is a single organism made up of cells among which there is a simple but obvi- ous difference in structure and function ; in other words , whether Volvox is a colony of one - celled animals , of Pro- tozoa , or is a ...
... distinct organisms or is a single organism made up of cells among which there is a simple but obvi- ous difference in structure and function ; in other words , whether Volvox is a colony of one - celled animals , of Pro- tozoa , or is a ...
Стр. 41
... distinct tissues and organs are foreshadowed . The individuals of Hydra live , usually , distinct from each other . There is no tree - like colony , as with the sponges . But most of the other polyps do live in this colonial manner ...
... distinct tissues and organs are foreshadowed . The individuals of Hydra live , usually , distinct from each other . There is no tree - like colony , as with the sponges . But most of the other polyps do live in this colonial manner ...
Стр. 42
... distinct forms . This appearance of one kind of animal in two forms is called dimorphism . We shall see later that one kind of animal may appear in more than two forms ; such a condition is called polymorphism . In alternation of gen ...
... distinct forms . This appearance of one kind of animal in two forms is called dimorphism . We shall see later that one kind of animal may appear in more than two forms ; such a condition is called polymorphism . In alternation of gen ...
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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.