Heredity and Evolution in PlantsP. Blakiston's Son & Company, 1920 - 265 стор. |
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Algæ anatomy ancestors Angiosperms appear aquatic archegonia beans become Botanic Garden botanists botany breeding called cells changes CHAPTER characters chlorophyll chromosomes cone Cordaitales cotyledon Cycadales Cycadeoidea Cycadofilicales cycads Darwin derived Devonian dicotyledons discontinuous embryo endemic environment evidence evolution evolutionary example fact fern fertilized egg Filicales flora flowers foliage-leaves forms fossil fossil record gametes gametophyte genera genus geographical distribution geological Ginkgoales gradually Gymnosperms heredity hybrid hypothesis illustrated inheritance islands known Lamarckiana land large number leaf leaves Lepidodendrales liverworts Lycopodiales mature Mendel method miles modern monocotyledons mosses mutation natural selection North America ocean organs paleobotany Paleozoic parent phyte plants and animals possess present primitive produced prothallus protoplasm Pteridophyta regions reproductive resemble result rhizoids rocks seed-bearing seeds showing specimens sperms sporangia spores sporo sporophyte stamens stem strobilus structure surface theory tion tissue tree variety various vascular vegetative Vries Wieland woody wrinkled York
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Сторінка 99 - There is grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being evolved.
Сторінка 96 - If turf which has long been mown — and the case would be the same with turf closely browsed by quadrupeds — be let to grow, the more vigorous plants gradually kill the less vigorous though fully grown plants; thus out of twenty species growing on a little plot of mown turf (three feet by four) nine species perished, from the other species being allowed to grow up freely.
Сторінка 194 - 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.
Сторінка 99 - These laws, taken in the largest sense, being Growth with Reproduction; Inheritance which is almost implied by reproduction, Variability from the indirect and direct action of the external conditions of life, and from use and disuse...
Сторінка 119 - But as my conclusions have lately been much misrepresented, and it has been stated that I attribute the modification of species exclusively to natural selection, I may be permitted to remark that in the first edition of this work, and subsequently, I placed in a most conspicuous position — namely, at the close of the Introduction — the following words : " I am convinced that natural selection has been the main but not the exclusive means of modification.
Сторінка 98 - It is interesting to contemplate a tangled bank, clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth...
Сторінка 96 - The mistletoe is dependent on the apple and a few other. trees, but can only in a far-fetched sense be said to struggle with these trees, for, if too many of these parasites grow on the same tree, it will languish and die.
Сторінка 118 - ... variations ; aided in an important manner by the inherited effects of the use and disuse of parts ; and in an unimportant manner, that is in relation to adaptive structures, whether past or present, by the direct action of external conditions, and by variations which seem to us in our ignorance to arise spontaneously.
Сторінка 96 - Darwin introduced the struggle for existence in the third chapter of the Origin of Species, writing about it as follows: I should premise that I use the term struggle for existence in a large and metaphorical sense, including dependence of one being on another, and including (which is more important) not only the life of the individual, but success in leaving progeny.
Сторінка 96 - A plant which annually produces a thousand seeds, of which only one on an average comes to maturity, may be more truly said to struggle with the plants of the same and other kinds which already clothe the ground. The mistletoe is dependent on the apple and a few other trees, but can only in a farfetched sense be said to struggle with these trees, for if too many of these parasites grow on the same tree, it languishes and dies. But several seedling mistletoes, growing close together on the same branch,...