Animal Life: A First Book of ZoölogyD. Appleton, 1900 - Всего страниц: 329 |
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Стр. vii
... egg , 79. - Embryonic and post - em- bryonic development , 80. - Continuity of development , 83. - De- velopment after the gastrula stage , 84. - Divergence of develop- PAGE 1 24 50 63 78 CHAPTER ment , 84. — The laws or general facts vii.
... egg , 79. - Embryonic and post - em- bryonic development , 80. - Continuity of development , 83. - De- velopment after the gastrula stage , 84. - Divergence of develop- PAGE 1 24 50 63 78 CHAPTER ment , 84. — The laws or general facts vii.
Стр. 2
... stages of a many - celled animal . The animal cell is rarely typically cellular in character —that is , it is rarely in the condition of a tiny sac or box of symmetrical shape . Plant cells are often of this char- acter . The primitive ...
... stages of a many - celled animal . The animal cell is rarely typically cellular in character —that is , it is rarely in the condition of a tiny sac or box of symmetrical shape . Plant cells are often of this char- acter . The primitive ...
Стр. 8
... stages of division . The dark , white- margined spot in the interior is the nucleus . - After F. E. SCHULZE . is constantly assimilated and added to it . The Amaba grows . But there seem to be some fixed limits to the extent of this ...
... stages of division . The dark , white- margined spot in the interior is the nucleus . - After F. E. SCHULZE . is constantly assimilated and added to it . The Amaba grows . But there seem to be some fixed limits to the extent of this ...
Стр. 14
... stages in the conjugation and spore forming of Gregarina poly- morpha ( after KOELLIKER ) . and hence has no swimming cilia like Paramecium and the young Vorticella . It does need to cling to the inner wall of the alimentary canal of ...
... stages in the conjugation and spore forming of Gregarina poly- morpha ( after KOELLIKER ) . and hence has no swimming cilia like Paramecium and the young Vorticella . It does need to cling to the inner wall of the alimentary canal of ...
Стр. 27
... stage . " That is , the cell remains dormant for a shorter or longer time . It may thus tide over a drought or a ... stages in the conjugation and formation of the resting spore . A , two cells just fused ; B , the two cells completely ...
... stage . " That is , the cell remains dormant for a shorter or longer time . It may thus tide over a drought or a ... stages in the conjugation and formation of the resting spore . A , two cells just fused ; B , the two cells completely ...
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adaptation adult alimentary canal Amaba ants become bees birds butterfly called cavity chitin CLASS colony color complex animals composed conjugation coral crab crustaceans degeneration differentiation digestion divide ectoderm egg cells existence eyes fauna feed female fish flagella free-swimming function gastrula Globigerinæ habits hatched higher animals host Hydra inclosed increase individuals insects instinct intestine islands jelly-fishes kinds of animals larva larvæ layer live male mals mammals many-celled animals mass medusa mouth opening naturalists nerve nest nucleus ocean one-celled outer oxygen Pandorina papillæ Paramecium parasites parent perform plants polyp prey primitive processes produced protective resemblance protoplasm Protozoa pseudopods pupa queen Radiolaria reflex action reproductive cells Sacculina sea-anemone shape shell simple simplest animals single cell special sense species sperm cells spherical spiders sponge stage structure substance surface swimming tentacles tion 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.