The Physical Basis of SocietyD. Appleton and Company, 1916 - 406 من الصفحات |
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الصفحة 18
... light , the water may evaporate ere plant roots are benefited ; if very heavy , they may beat down and destroy crops and wash the soil . Fog may bring little precipitation , but may produce many of the same effects and be very helpful ...
... light , the water may evaporate ere plant roots are benefited ; if very heavy , they may beat down and destroy crops and wash the soil . Fog may bring little precipitation , but may produce many of the same effects and be very helpful ...
الصفحة 26
... light is responsible for the strati- fication just mentioned , for it seems these dwellers of the depths come to the surface only at night . Practically no light rays penetrate more than 350 feet below the surface of the water . Owls ...
... light is responsible for the strati- fication just mentioned , for it seems these dwellers of the depths come to the surface only at night . Practically no light rays penetrate more than 350 feet below the surface of the water . Owls ...
الصفحة 27
... light . In ponds the snails seek a faint light , being found in the lightest spots on the darkest days . Activity is determined by structure . The fish swims because it is so constructed that it can't help swimming if it moves . We have ...
... light . In ponds the snails seek a faint light , being found in the lightest spots on the darkest days . Activity is determined by structure . The fish swims because it is so constructed that it can't help swimming if it moves . We have ...
الصفحة 34
... light and cold , nature makes no mistake , but selects a color to exclude the light . Hence in all cold , light countries , i.e. , steppes , plains and the arctics , there is pigmentation of a color in the lower end of the spectrum ...
... light and cold , nature makes no mistake , but selects a color to exclude the light . Hence in all cold , light countries , i.e. , steppes , plains and the arctics , there is pigmentation of a color in the lower end of the spectrum ...
الصفحة 48
... light during the day because of the pressure of sunlight , and that if taken into a dark room they would be found to ... light all day , one observes the little lamps light up and flash out one by one like coruscating diamonds in ...
... light during the day because of the pressure of sunlight , and that if taken into a dark room they would be found to ... light all day , one observes the little lamps light up and flash out one by one like coruscating diamonds in ...
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agriculture America aniline appeared Asia average bacteria basis bees believe birds black bass body breeding carbon carbon dioxid carbonic acid cause cent century changes characters chromosomes civilization climate coal color combined considered crops Darwin death destroyed discovered discoveries disease early earth eggs elements environment Europe European evidence evolution exist fact favorable feeble-minded female fish forms germ cells groups heat hence heredity human Ibid idea Inasmuch inches increase individuals influence inheritance insects iron Kallikak Family known Lamarck land large numbers larvæ later less light Linnæus living lower Luther reigned male man's mated natural selection nature Negro normal organisms ovum oxygen parents physical plants and animals possible produced race realize seeds smallpox social soil species square mile substances temperature thought tion tropics women yellow yellow fever
مقاطع مشهورة
الصفحة 155 - Some drill and bore The solid earth, and from the strata there Extract a register, by which we learn, That he who made it, and revealed its date To Moses, was mistaken in its age.
الصفحة 139 - I happened to read for amusement ' Malthus on Population,' and being well prepared to appreciate the struggle for existence which everywhere goes on from long-continued observation of the habits of animals and plants, it at once struck me that under these circumstances favourable variations would tend to be preserved, and unfavourable ones to be destroyed. The result of this would be the formation of new species. Here then I had at last got a theory by which to work...
الصفحة 58 - Near villages and small towns I have found the nests of humble-bees more numerous than elsewhere, which I attribute to the number of cats that destroy the mice.
الصفحة 139 - In October 1838, that is, fifteen months after I had begun my systematic enquiry, I happened to read for amusement Malthus on Population, and being well prepared to appreciate the struggle for existence which everywhere goes on from long-continued observation of the habits of animals and plants, it at once struck me that under these circumstances favourable variations would...
الصفحة 54 - It may be doubted whether there are many other animals which have played so important a part in the history of the world, as have these lowly organized creatures.
الصفحة 186 - The two parents between them contribute on the average onehalf of each inherited faculty, each of them contributing onequarter of it. The four grandparents contribute between them one-quarter, or each of them one-sixteenth ; and so on, the sum of the series i + J + i + TV + , being equal to 1, as it should be.
الصفحة 126 - This fool wishes to reverse the entire science of astronomy; but sacred Scripture tells us that Joshua commanded the sun to stand still, and not the earth.
الصفحة 58 - I am tempted to give one more instance showing how plants and animals, remote in the scale of nature, are bound together by a web of complex relations.
الصفحة 159 - I can conceive in biology would be the discovery of the instability which leads to the continual division of the cell. When I look at a dividing cell I feel as an astronomer might do if he beheld the formation of a double star: that an original act of creation is taking place before me.
الصفحة 58 - I have also found that the visits of bees are necessary for the fertilization of some kinds of clover; for instance, 20 heads of Dutch clover (Trifolium repens) yielded 2,290 seeds, but 20 other heads protected from bees produced not one.