Animal Life: A First Book of ZoölogyD. Appleton, 1900 - Всего страниц: 329 |
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Стр. 34
... digestion . Each cell takes up food and digests it . The water cur- rents also bring air to these same cells , and thus the sponge breathes . Although the sponge as a whole can not move , does not possess the power of locomotion , yet ...
... digestion . Each cell takes up food and digests it . The water cur- rents also bring air to these same cells , and thus the sponge breathes . Although the sponge as a whole can not move , does not possess the power of locomotion , yet ...
Стр. 39
... digestive fluid . The food captured by the tentacles and taken in through the mouth opening disintegrates in the body cavity , or diges- tive cavity , as it may be called . The digestive fluid se- creted by the gland cells of the ...
... digestive fluid . The food captured by the tentacles and taken in through the mouth opening disintegrates in the body cavity , or diges- tive cavity , as it may be called . The digestive fluid se- creted by the gland cells of the ...
Стр. 41
... digestion of the food ; some are specially contractile , and on them the movements of the body depend , while others are specially irritable or sensitive , and on them the body depends for knowledge of the contact of prey or enemies ...
... digestion of the food ; some are specially contractile , and on them the movements of the body depend , while others are specially irritable or sensitive , and on them the body depends for knowledge of the contact of prey or enemies ...
Стр. 43
... digestive cavity is differentiated into central and peripheral portions . In these dimorphic polyps the fixed polyp individuals reproduce by the simple way of budding , while the medusa individuals reproduce by producing special ...
... digestive cavity is differentiated into central and peripheral portions . In these dimorphic polyps the fixed polyp individuals reproduce by the simple way of budding , while the medusa individuals reproduce by producing special ...
Стр. 49
... digestive cavity becomes complex and composed of different portions ; the reproduc- tive cells are formed by special organs , and the distinction between the egg cells and the sperm cells - that is , be- tween the female reproductive ...
... digestive cavity becomes complex and composed of different portions ; the reproduc- tive cells are formed by special organs , and the distinction between the egg cells and the sperm cells - that is , be- tween the female reproductive ...
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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.