Animal Life: A First Book of ZoölogyD. Appleton, 1900 - Всего страниц: 329 |
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Стр. 15
... outer wall of the cyst breaks and the spores fall out , each to grow and develop into a new Gre- garina . In some species there are fine ducts or canals leading from the center of the cyst through the wall to the outside , and through ...
... outer wall of the cyst breaks and the spores fall out , each to grow and develop into a new Gre- garina . In some species there are fine ducts or canals leading from the center of the cyst through the wall to the outside , and through ...
Стр. 27
... outer wall breaks and the pro- toplasm issues as a large free- swimming cell , which soon di- vides into sixteen daughter cells which constitute a new colony . A B 16. Eudorina . - Another colo- nial protozoan which much re- sembles ...
... outer wall breaks and the pro- toplasm issues as a large free- swimming cell , which soon di- vides into sixteen daughter cells which constitute a new colony . A B 16. Eudorina . - Another colo- nial protozoan which much re- sembles ...
Стр. 33
... outer wall is cut away to show the in- side . sort of skeleton for the support of FIG . 17. - One of the simplest the soft body mass . All over the outer surface of the body are scat- tered fine openings or pores , which lead through ...
... outer wall is cut away to show the in- side . sort of skeleton for the support of FIG . 17. - One of the simplest the soft body mass . All over the outer surface of the body are scat- tered fine openings or pores , which lead through ...
Стр. 38
... outer and an inner layer of cells and a thin non - cellular membranous layer between them . The tentacles are hol- low and are simple extensions of the body wall . The cells of the outer layer , or ectoderm , are not all alike . Some ...
... outer and an inner layer of cells and a thin non - cellular membranous layer between them . The tentacles are hol- low and are simple extensions of the body wall . The cells of the outer layer , or ectoderm , are not all alike . Some ...
Стр. 40
... outer surface of the body a little bud which is composed , at first , of ectoderm cells alone ; but soon it is evident that it is a budding , or outpushing , of the whole body wall , ectoderm , endoderm , and middle membrane . In a few ...
... outer surface of the body a little bud which is composed , at first , of ectoderm cells alone ; but soon it is evident that it is a budding , or outpushing , of the whole body wall , ectoderm , endoderm , and middle membrane . In a few ...
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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.