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action activity American animals appear become believe birds body called cause cells cent changes characters closely color common complete considerable considered continue described determine direction discussion effect eggs environment evidence evolution existence experimental experiments fact factors families fauna female fishes forms four gametophyte genera genus give given growing growth hand important indicate individuals interesting known laboratory later less limits living lower male material matter means method nature normal noted nucleus observations obtained occur organs origin parasites physiological plants position possible present probably problem produce Professor published question recent reference regard regeneration region relation remains represented seems selection shown side similar single species specimens stage structure theory tion true University usually variation various
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 582 - 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...