The Principles of Biology, Nide 2D. Appleton, 1871 |
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Acrogens actions agamogenesis aggregates alimentary canal animals arise axes axillary bud axis become bilateral symmetry bones branches capillaries cause cells chlorophyll colloids colour common compound compressions connexion continue contrast creatures degree differentiation direct environment equilibration equilibrium evidence evolution exposed facts fertility flowering plants flowers foliar organs fronds functions further genesis greater growing growth habitually Hence higher homologous Hydrozoa hypothesis implies incident forces increase individuals inference inner integration intermittent mechanical Jungermanniacea kind layer leaf leaves less liquid mass mechanical mid-rib mode modifications molecular molecules morphological motion multiplication muscles natural selection notochord nutriment nutrition occur ossification outer pass petioles Phænogams physiological plants portion produced protoplasm radial relations reproductive result second order secondary segments shape shoot sides similarly species stem strains structure substance supply surface tion tissue transverse types umbellules units unlike vascular vascular system vertebral column Vertebrata vertebrate vessels
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Sivu 196 - They all of them amount to this: — that in the actions and reactions of force and matter, an unlikeness in either of the factors necessitates an unlikeness in the effects ; and that in the absence of unlikeness in either of the factors the effects must be alike.
Sivu 485 - ... perfection — after having, at the same time, developed the intellect into complete competency for its work, and the feelings into complete fitness for social life — after having done all this, the pressure of population, as it gradually finishes its work, must gradually bring itself to an end.
Sivu 119 - How far such differences are due to the positions of the parts in the bud ; how far the respective spaces available for the parts when unfolded affect them ; and how far the parts are rendered unlike by unlikenesses in their relations to light, it is difficult to say. Probably, these several factors operate in all varieties of proportion.
Sivu 417 - If, therefore, it is in a state of excessive activity, it will necessarily draw off from the individual fabric some portion of the aliment destined for its maintenance. It may be universally observed, that when the nutritive functions are particularly active in supporting the individual...
Sivu 69 - The sponge represents a kind of subaqueous city, where the people are arranged about the streets and roads in such a manner that each can easily appropriate his food from the water as it passes along.
Sivu 484 - It produced the original diffusion of the race. It compelled men to abandon predatory habits and take to agriculture. It led to the clearing of the Earth's surface. It forced men into the social state ; made social organization inevitable ; and has developed the social sentiments. It has stimulated to progressive improvements in production, and to increased skill and intelligence.
Sivu 464 - ... them may be reasonably attributed to the overtaxing of their brains — an overtaxing which produces a serious reaction on the physique. This diminution of reproductive power is not shown only by the greater frequency of absolute sterility ; nor is it shown only in the earlier cessation of childbearing ; but it is also shown in the very frequent inability of such women to suckle their infants. In its full sense, the reproductive power means the power to bear a well-developed infant, and to supply...
Sivu 480 - ... life, we infer will continue to take place. . . But everywhere and always, evolution is antagonistic to procreative dissolution. Whether it be in greater growth of the organs which subserve self-maintenance, whether it be in their added complexity of structure, or whether it be in their higher activity, the abstraction of the required materials implies a diminished reserve of materials for race-maintenance.
Sivu 477 - From the beginning, pressure of population has been the proximate cause of progress. All mankind in turn subject themselves more or less to the discipline described: they either may, or may not advance under it, but in the nature of things only those who do advance under it eventually survive.