The American Naturalist, Volume 42Essex Institute, 1908 |
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Página 53
... CONTINUE IN SPITE OF FREE - CROSSING ? As we have already shown in certain species of Hawai- ian snails , a sudden mutation may arise , which by its very constitution is prevented from crossing with the parent stock ; and in such cases ...
... CONTINUE IN SPITE OF FREE - CROSSING ? As we have already shown in certain species of Hawai- ian snails , a sudden mutation may arise , which by its very constitution is prevented from crossing with the parent stock ; and in such cases ...
Página 53
... CONTINUE IN SPITE OF FREE - CROSSING ? As we have already shown in certain species of Hawai- ian snails , a sudden mutation may arise , which by its very constitution is prevented from crossing with the parent stock ; and in such cases ...
... CONTINUE IN SPITE OF FREE - CROSSING ? As we have already shown in certain species of Hawai- ian snails , a sudden mutation may arise , which by its very constitution is prevented from crossing with the parent stock ; and in such cases ...
Página 189
... continue to believe that sexual selection is necessary to account for secondary sexual characters . 12. An organ once functionally lost is never perma- nently regained by natural selection or any of its hypo- thetical substitutes . A ...
... continue to believe that sexual selection is necessary to account for secondary sexual characters . 12. An organ once functionally lost is never perma- nently regained by natural selection or any of its hypo- thetical substitutes . A ...
Página 192
... continue longer than the fad of its breeding remains undiminished ? 3. A species is a type which varies only within narrow limits . The jungle fowl is fairly constant in nature . Its extraordinary variability is seen in the domestic ...
... continue longer than the fad of its breeding remains undiminished ? 3. A species is a type which varies only within narrow limits . The jungle fowl is fairly constant in nature . Its extraordinary variability is seen in the domestic ...
Página 221
... continue . Why mere tyros , wholly untrained in the underlying principles of the science of classification , should be allowed to contribute to the confusion of taxonomy is a matter which may well make us marvel . But there have been ...
... continue . Why mere tyros , wholly untrained in the underlying principles of the science of classification , should be allowed to contribute to the confusion of taxonomy is a matter which may well make us marvel . But there have been ...
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Termos e frases comuns
AMERICAN NATURALIST Amphibia animals Antedon apotropic appear birds body botanical botanists cause cells cent centrosome changes characters chemical color crinoids described Diplodocus dwarf dwarf faunas Edition eggs embryo endophyte environment evidence evolution experimental experiments fact factors families fasciation fauna female fertilization fishes forms gametes gametophyte genera genus germination give growth haustoria hybrids Illinois important individuals insect investigation isolation known L. H. BAILEY laboratory larvæ latency less living male matter ment method migration mitosis morphological mottled moult mutation nature nerve normal nucleus observations occur oogonium organs origin paper parasites phenogams physiological plants present probably problem produce Professor protoplasm protozoa question radium recent regard regeneration region relation rotifers seed seems sex-tendency somites species specimens spirochetes sporophyte stage Stoma structure substance temperature theory tion tissue trichomes variation vertebrate w[cs zoology
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Página 234 - In short, we shall have to treat species in the same manner as those naturalists treat genera, who admit that genera are merely artificial combinations made for convenience. This may not be a cheering prospect ; but we shall at least be freed from the vain search for the undiscovered and undiscoverable essence of the term species.
Página 389 - It is quite true that, to the best of my judgment, the argumentation which applies to brutes holds equally good of men; and, therefore, that all states of consciousness in us, as in them, are immediately caused by molecular changes of the brain-substance.
Página 389 - The consciousness of brutes would appear to be related to the mechanism of their body simply as a collateral product of its working, and to be as completely without any power of modifying that working, as the steam-whistle which accompanies the work of a locomotive engine is without influence upon its machinery.
Página 71 - Given any species in any region, the nearest related species is not likely to be found in the same region, nor in a remote region, but in a neighboring district, separated from the first by a barrier of some sort, or at least by a belt of country the breadth of which gives the effect of a barrier.
Página 249 - I HAVE hitherto sometimes spoken as if the variations — so common and multiform in organic beings under domestication, and in a lesser degree in those in a state of nature — had been due to chance. This, of course, is a wholly incorrect expression, but it serves to acknowledge plainly our ignorance of the cause of each particular variation.
Página 389 - It seems to me that in men, as in brutes, there is no proof that any state of consciousness is the cause of change in the motion of the matter of the organism.
Página 580 - Subscription price $6 per year, or 50 cents a number, postage prepaid in the United States; $6.25 to Canada; $6.40 to foreign subscribers of countries in the Postal Union.
Página 389 - If these positions are well based, it follows that our mental conditions are simply the symbols in consciousness of the changes which take place automatically in the organism...
Página 117 - ... of individual development had to be taken into account ; and, at present, the study of ancestral evolution introduces a new element of likeness and unlikeness which is not only eminently deserving of recognition, but must ultimately predominate over all others. A classification which shall represent the process of ancestral evolution is, in fact, the end which the labors of the philosophical taxonomist must keep in view. But it is an end which cannot be attained until the progress of palaeontology...
Página 696 - In no case may we interpret an action as the outcome of the exercise of a higher psychical faculty if it can be interpreted as the outcome of one which stands lower in the psychological scale.