Life and Evolution: An Introduction to General BiologyHarcourt, Brace, 1926 - Всего страниц: 449 |
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Стр. 11
... side sources , and for the most part directly or indirectly from the radiant energy of the sun . One of the most important scientific discoveries of the nineteenth century was the law of the conservation of energy , which was ...
... side sources , and for the most part directly or indirectly from the radiant energy of the sun . One of the most important scientific discoveries of the nineteenth century was the law of the conservation of energy , which was ...
Стр. 13
... sides of the question are represented by able and scholarly defenders . The question at issue is one of fundamental importance , and one to be kept in mind by the reader as he goes through the rest of this volume . When he gets to the ...
... sides of the question are represented by able and scholarly defenders . The question at issue is one of fundamental importance , and one to be kept in mind by the reader as he goes through the rest of this volume . When he gets to the ...
Стр. 34
... sides of the nucleus , but usually before this has occurred the nuclear wall has broken down and other changes have taken place which have effected a remarkable transforma- tion of the nuclear contents . Mitosis involves parallel series ...
... sides of the nucleus , but usually before this has occurred the nuclear wall has broken down and other changes have taken place which have effected a remarkable transforma- tion of the nuclear contents . Mitosis involves parallel series ...
Стр. 39
... side of a thin slip of glass , the whole being kept in a moist chamber to prevent evaporation . By means of glass needles drawn out to an extreme fineness and operated by a system of screws so as to permit of slow and accurately ...
... side of a thin slip of glass , the whole being kept in a moist chamber to prevent evaporation . By means of glass needles drawn out to an extreme fineness and operated by a system of screws so as to permit of slow and accurately ...
Стр. 44
... side in a , and from above in b ; c , cuboidal epithelium ; d , epithe- lium several cells in thickness - the deepest cells are columnar , but the others be- come more flattened as they are pushed outward ; e , columnar ciliated ...
... side in a , and from above in b ; c , cuboidal epithelium ; d , epithe- lium several cells in thickness - the deepest cells are columnar , but the others be- come more flattened as they are pushed outward ; e , columnar ciliated ...
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algæ Amoeba ants appearance B₁ b₂ bacteria become birds blood body called carried causes cavity cell division centrosomes characters chemical chromosomes cœlom colony color commonly crustaceans cytoplasm Darwin digestive disease ectoderm eggs embryo Eocene epithelium evolution fact factors female fermentation fertilized fibers fluid forms function gametes gastrula germ cells germ plasm gill glands green hereditary heredity higher animals human Hydra hydroids individuals inheritance insects intestine kinds known large number larvæ later layer living lower male mammals Mendelian micronucleus mitosis muscles natural nerve nest normal notochord nucleus occur organisms outer ovum pairs parasites parents parthenogenesis peculiar period plants and animals pollen primitive produce progeny proteins protoplasm queen regeneration region relation relatively reproduction reptiles result secretion sex cells sexual species sperm spores stage structure substance surface synapsis theory tion tissue usually ventral vertebrates vessels wall worms X chromosome young
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Стр. 422 - Of all the western stars, until I die. It may be that the gulfs will wash us down: It may be we shall touch the Happy Isles, And see the great Achilles, whom we knew. Tho' much is taken, much abides; and tho...
Стр. 349 - I look at the geological record as a history of the world imperfectly kept, and written in a changing dialect; of this history we possess the last volume alone, relating only to two or three countries. Of this volume, only here and there a short chapter has been preserved; and of each page, only here and there a few lines.
Стр. 392 - It may metaphorically be said that natural selection is daily and hourly scrutinizing, throughout the world, the slightest variations; rejecting those that are bad, preserving and adding up all that are good; silently and sensibly working, whenever and wherever opportunity offers, at the improvement of each organic being in relation to its organic and inorganic conditions of life.
Стр. 392 - ... those that are bad, preserving and adding up all that are good; silently and insensibly working, whenever and wherever opportunity offers, at the improvement of each organic being in relation to its organic and inorganic conditions of life. We see nothing of these slow changes in progress until the hand of time has marked the lapse of ages, and then so imperfect is our view into long-past geological ages that we see only that the forms of life are now different* from what they formerly were.
Стр. 247 - Battle within battle must ever be recurring with varying success; and yet in the long-run the forces are so nicely balanced, that the face of nature remains uniform for long periods of time, though assuredly the merest trifle would often give the victory to one organic being over another.
Стр. 395 - Given any species in any region, the nearest related species is not likely to be found in the same region nor in a remote region, but in a neighboring district separated from the first by a barrier of some sort.
Стр. 10 - Life is a series of definite and successive changes, both of structure and composition, which take place within an individual without destroying its identity.
Стр. 247 - Azara and Rengger have shown that this is caused by the greater number in Paraguay of a certain fly, which lays its eggs in the navels of these animals when first born. The increase of these flies, numerous as they are, must be habitually checked by some means, probably by other parasitic insects. Hence, if certain insectivorous birds were to decrease in Paraguay, the parasitic insects would probably increase; and this would lessen the number of the navel-frequenting flies — then cattle and horses...
Стр. 247 - Scotch fir ; but in several parts of the world insects determine the existence of cattle. Perhaps Paraguay offers the most curious instance of this ; for here neither cattle nor horses nor dogs have ever run wild, though they swarm southward and northward...
Стр. 220 - ... mandibles have lost their teeth, and have become mere nippers, deadly weapons indeed, but useless except in war. They have lost the greater part of their instincts : their art, that is, the power of building ; their domestic habits, for they take no...