The Origin of Species by Means of Natural Selection; Or, the Preservation of Favored Races in the Struggle for Life ...A.L. Burt, 1890 - 538페이지 |
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384 페이지
... seeds after- word germinated ; the ripe seeds of Helosciadium surk in two days , when dried they floated for above ninety days , and afterward germinated . Altogether , out of the ninety- four dried plants , eighteen floated for above ...
... seeds after- word germinated ; the ripe seeds of Helosciadium surk in two days , when dried they floated for above ninety days , and afterward germinated . Altogether , out of the ninety- four dried plants , eighteen floated for above ...
385 페이지
... seeds or fruit which , as Alph . de Candolle has shown , generally have restricted ranges , could hardly be trans- ported by any other means . Seeds may be occasionally transported in another manner . Drift timber is thrown up on most ...
... seeds or fruit which , as Alph . de Candolle has shown , generally have restricted ranges , could hardly be trans- ported by any other means . Seeds may be occasionally transported in another manner . Drift timber is thrown up on most ...
408 페이지
... seeds ; I have tried several little experiments , but will here give only the most striking case : I took in February three tablespoonfuls of mud from three different points , beneath water , on the edge of a little pond ; this mud when ...
... seeds ; I have tried several little experiments , but will here give only the most striking case : I took in February three tablespoonfuls of mud from three different points , beneath water , on the edge of a little pond ; this mud when ...
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adapted admit affinities allied species America ancient appear Asa Gray beak become bees believe belonging birds breeds cause cells characters climate closely allied color continued crossed crustaceans degree developed difficulty distinct species divergence domestic doubt effects eggs embryo existing extinct extremely facts favorable fertility flowers formation forms fossil Fritz Müller genera genus geological geological period Glacial period gradations greater number groups of species habits Hence hybrids hybrids produced important individuals inhabitants inherited insects instance instincts intercrossing intermediate intervals kind lamellæ larvæ less living male mammals manner marsupials migration modified descendants natural selection naturalists nearly nest occasionally oceanic islands offspring organs parent peculiar perfect pigeons pistil pollen present principle probably produced quadrupeds ranked remarked resemblance rudimentary seeds sexual selection Silurian slight South America stamens sterility structure successive suppose tend theory tion variability variations varieties vary whole widely different wings young