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 |
도서 본문에서
19개의 결과 중 1 - 3개
87 페이지
... pistil , and four stamens with shrivelled anthers , in which not a grain of polen can be detected . Having found a ... pistils alone in another flower or on another plant . In plants under culture and placed under new conditions of life ...
... pistil , and four stamens with shrivelled anthers , in which not a grain of polen can be detected . Having found a ... pistils alone in another flower or on another plant . In plants under culture and placed under new conditions of life ...
468 페이지
... pistil , with an hermaphrodite species , having of course a well - developed pistil , the rudiment in the hybrid offspring was much increased in size ; and this clearly shows that the rudimentary and perfect pistils are essentially ...
... pistil , with an hermaphrodite species , having of course a well - developed pistil , the rudiment in the hybrid offspring was much increased in size ; and this clearly shows that the rudimentary and perfect pistils are essentially ...
469 페이지
... pistil is to allow the pollen- tubes to reach the ovules within the ovarium . The pistil consists of a stigma supported on a style ; but in some Ĉom- positæ , the male florets , which of course cannot be fecun- dated , have a rudimentary ...
... pistil is to allow the pollen- tubes to reach the ovules within the ovarium . The pistil consists of a stigma supported on a style ; but in some Ĉom- positæ , the male florets , which of course cannot be fecun- dated , have a rudimentary ...
기타 출판본 - 모두 보기
자주 나오는 단어 및 구문
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 domestic doubt effects eggs embryo existing extinct extremely facts favorable females fertility flowers formation forms fossil Fritz Müller genera genus geological geological period gilt top Glacial period gradations greater number groups of species habits Hence hybrids hybrids produced important individuals inhabitants inherited insects instance instincts intercrossing intermediate kind lamellæ larvæ less living male mammals manner marsupials migration modified descendants natural selection naturalists nearly nest 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