On the Origin of Species by Means of Natural SelectionD. Appleton, 1870 - 440페이지 |
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92 페이지
... Gärtner , any in- Huence from the foreign pollen . When the stamens of a flower suddenly spring towards the pistil , or slowly move one after the other towards it , the contrivance seems adapted solely to ensure self - fertili- sation ...
... Gärtner , any in- Huence from the foreign pollen . When the stamens of a flower suddenly spring towards the pistil , or slowly move one after the other towards it , the contrivance seems adapted solely to ensure self - fertili- sation ...
218 페이지
... Gärtner also , makes the rule equally universal ; and he disputes the entire fertility of Kölrenter's ten cases . But in these and in many other cases , Gärtner is obliged carefully to count the seeds , in order to show that there is ...
... Gärtner also , makes the rule equally universal ; and he disputes the entire fertility of Kölrenter's ten cases . But in these and in many other cases , Gärtner is obliged carefully to count the seeds , in order to show that there is ...
219 페이지
... Gärtner were potted , and apparently were kept in a chamber in his house . That these processes are often injurious to the fertility of a plant cannot be doubt ed ; for Gärtner gives in his table about a score of cases of plants which ...
... Gärtner were potted , and apparently were kept in a chamber in his house . That these processes are often injurious to the fertility of a plant cannot be doubt ed ; for Gärtner gives in his table about a score of cases of plants which ...
220 페이지
... Gärtner was enabled to rear some hy- brids , carefully guiding them from a cross with either pure parent , for six or seven , and in one case for ten gen- erations , yet he asserts positively that their fertility never increased , but ...
... Gärtner was enabled to rear some hy- brids , carefully guiding them from a cross with either pure parent , for six or seven , and in one case for ten gen- erations , yet he asserts positively that their fertility never increased , but ...
221 페이지
... Gärtner that some degree of sterility between distinct species is a universal law of nature . He experimentised on some of the very same species as did Gärtner . The difference in their re- sults may , I think , be in part accounted for ...
... Gärtner that some degree of sterility between distinct species is a universal law of nature . He experimentised on some of the very same species as did Gärtner . The difference in their re- sults may , I think , be in part accounted for ...
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accumulated adapted affinities allied species America amount ancient animals appear become bees believe birds breeds cause cells characters cirripedes climate closely allied colour continuous crossed crustaceans degree difficulty distinct species divergence domestic doubt embryo endemic Europe existing exterminated extinct extremely facts favourable fertility flowers formations forms fossil Gärtner genera genus geological geological period Glacial period gradations greater number groups of species habits Hence hermaphrodites hybrids hybrids produced important individuals inhabitants inherited insects instance instincts intercrossing intermediate land larvæ laws less living look male mammals manner migration modification modified descendants natural selection naturalists nearly nest offspring organic organisation perfect pigeons pistil plants pollen present principle probably produced progenitor ranked reciprocal crosses remarked resemble rudimentary seeds sexual selection Silurian slight South America sterility structure struggle successive suppose swimbladder tend theory tion trees variability variation varieties vary whole widely