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activity animals appear become believe birds body called cause cells changes characters closely color common complete conclusion considerable considered continue cross cytoplasm definite described determined direction discussion effect eggs embryo environment evidence evolution existence experimental experiments fact factors families fauna female fishes forms four gametophyte genera genus give given growth hand important increase indicate individuals interesting isolation known later leaves less limits living lower male material means method nature normal noted nucleus observations obtained occur organs origin parasites period plants position possible present probably problem produce question recent regard regeneration region relation remains represented seems selection separate shown side similar single species specimens stage structure taken temperature tion tissue true University usually variation various whole
Strana 244 - 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.
Strana 413 - 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.
Strana 413 - 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.
Strana 73 - 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.
Strana 261 - 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.
Strana 415 - A scorner of physic once said that nature and disease may be compared to two men fighting, the doctor to a blind man with a club, who strikes into the melee, sometimes hitting the disease, and sometimes hitting nature.
Strana 413 - 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.
Strana 556 - In a general way, the correlation of size with geographical distribution may be formulated in the following propositions : 1. The maximum physical development of the individual is attained where the conditions of environment are most favorable to the life of the species. Species being primarily limited in their distribution by climatic conditions, their representatives living at or near either of their respective latitudinal boundaries are more or less unfavorably affected by the influences that...
Strana 121 - ... 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...
Strana 594 - ... though usually less extensive, and always of a lower taxonomic rank, has done more than any other single thing to advance the science of Zoology ; for the whole theory of evolution turns, as it were, upon this point. It is therefore obvious that nearly all that has been affirmed of generic names may be here reaffirmed of specific names. Points requiring further comment are comparatively trivial, and purely technical. Specific and subspecific names (here conveniently treated together, as were...