Annals & Magazine of Natural HistoryTaylor & Francis, Limited, 1857 |
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Altres edicions - Mostra-ho tot
Frases i termes més freqüents
abdomen acetabula Algæ angles animal antennæ antheridia apex apice appear archegonium basal base belong birds body Brachiopoda brown canal cavity cells cephalothorax characters cilia colour Decapoda described distinct dorsal eggs elytra embryo embryo-sac examined extremity fecundation female filaments Foraminifera former furnished genera genus germinal vesicle granules hairs head Hectocotylus Hist inches individuals inner insect interfemoral membrane joint latter legs length less Loligo longitudinal lower male margin membrane middle Museum naturalists nature nearly nigris observed occur organs orifice outer ovules ovum pair palpi papillæ peculiar pedibus plants plates pollen-tube portion posterior present prothallium regard remarkable resemblance rounded rows Scutellum seen segment sér sexual side siphuncle slightly species specimens spermatozoids spines spores spot structure subtus suckers surface tail tarsi teeth thick thorax tibiæ tion transverse Tremoctopus upper whilst wings
Passatges populars
Pàgina 420 - If so, there was, nevertheless, during the nineteenth century an "animal" instinct, if I may use that expression, which carried the country onward in spite of itself. And there was also, at the end of the last century and at the beginning of the present, the illusion that a community had taken form.
Pàgina 484 - Variations of Species. But there are variations in species, and this is our next topic. The principles already considered teach, as we believe, that each species has its specific value as a unit, which is essentially permanent or indestructible by any natural source of change ; and we have, therefore, to admit in the outset, if these principles are true, that variations have their limits, and cannot extend to the obliteration of the fundamental characteristics of a species. To understand these variations,...
Pàgina 484 - ... of this force to other bodies, or kinds, amounts or conditions of force, upon which its variations depend. One great end of inorganic science is to study out the law of variables for each element or species. For this law is as much a part of an idea of the species, as the fundamental potentiality ; indeed, the one is a measure of the other. So again, a species in the organic kingdoms is subject to variations, and upon the same principle. Its very development depends on the appropriation of material...
Pàgina 482 - ... unnatural play of forces or arrangements to bring them about. Again, in the animal kingdom, there is the same aversion in nature to intermixture, and it is emotional as well as physical. The supposed cases of fertile hybridity are fewer than among plants. Moreover, in both kingdoms, if hybridity be begun, nature commences at once to purify herself as of an ulcer on the system. It is treated like a disease, and the energies of the species combine to throw it off. The short run of hybridity between...
Pàgina 486 - ... and those in organic nature adding to their numbers of representative individuals, but not kinds, by self-reproduction ; and all adding to their varieties by mutual reaction or sympathy. Thus, from the law within and the law without, under the Being above as the Author and sustainer of all law, the world has its diversity, the cosmos its fulness of beauty.
Pàgina 226 - The Red and Fluvio-marine Crags, tested by their mammalian fauna, must be considered as beds of the same geological age. Throughout this paper, for the sake of clearness, the subgeneric names have been used in designating the species. The author, finding that the name Elasmodon, applied to the third group of Elephants, in the
Pàgina 483 - ... species, all admitting of indefinite or nearly indefinite hybridization, in direct opposition to a grand principle elsewhere recognized in the organic kingdoms. It would have been using a process that produces impotence or nothing among animals, for the perpetuation and progress of the human race. There are other ways .of accounting for the limited productiveness of the mulatto, without appealing to a distinction of species. There are causes, independent of mixture, which are making the Indian...
Pàgina 486 - It may be remarked again, that we must consider this mode of reaching truth, by reasoning from the general to the special, as requiring also its complement, direct observation, to give unwavering confidence to the mind ; and we should therefore encourage research with a willingness to receive whatever results come from nature.
Pàgina 483 - In one kingdom, the inorganic, there is multiplication of kinds of units by combination, according to the law of multiples, and no reproduction ; while in the organic, there is reproduction of like from like and no multiplication of kinds by combination. And thus the two departments of living and dead nature widely diverge. Neither does the possibility of mere mixture among inorganic substances afford any analogy to sustain the idea of possible hybrid mixture indefinitely perpetuated, among living...
Pàgina 481 - ... connection with the pure or original stock. " 3. Mules that are wholly infertile among themselves, but may have issue for a generation or two by connection with one of the original stock. " 4. Mules that are wholly infertile among themselves, but may have issue through indefinite generations by connection for each with an individual of the original stock. " 5. Mules that are fertile among themselves through one or two generations. " 6. Mules that are fertile among themselves through many generations.