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adaptive ants aphids appear association areas atom become believe biological brain called causes centers central nervous system cerebellum cerebral cerebral cortex cerebrum changes chapter characteristics chemical chemotropism complex consciousness cortex Darwin Darwinian definite described determined discuss effectors eggs elements emotions evident example existence explain external forces feelings female fibers forms of behavior functions geotropism germ cell gregarious habit havior higher animals impulses indicated individual inherited instinctive actions intelligence involved Jennings light Loeb lower organisms mammals means mechanism Mendelian metazoa motor movements natural selection nerve nest neurones offspring organic evolution organic matter origin origin of species orthogenetic Paramecium parental phenomena phototaxis phototropism physiological probably processes protoplasm psychic Psychology reaction receptors reflex action relations reproduction result seems seen sensations sense organs sensory sexual social evolution species stimuli stincts structure takes place tendency term theory tion tropism true ungulata usually variations vertebrates Weismann young
Page 223 - Instinct is usually defined as the faculty of acting in such a way as to produce certain ends, without foresight of the ends, and without previous education in the performance.
Page 218 - We may, then, define an instinct as an inherited or innate psycho-physical disposition which determines its possessor to perceive, and to pay attention to, objects of a certain class, to experience an emotional excitement of a particular quality upon perceiving such an object, and to act in regard to it in a particular manner, or, at least, to experience an impulse to such action.
Page 135 - Behavior is merely a collective name for the most obvious and most easily studied of the processes of the organism, and it is clear that these processes are closely connected with, and are indeed outgrowths from, the more recondite internal processes.
Page 394 - In regard to bodily size or strength, we do not know whether man is descended from some small species, like the chimpanzee, or from one as powerful as the gorilla ; and, therefore, we cannot say whether man has become larger and stronger, or smaller and weaker, than his ancestors.
Page 260 - The latter appear invariably as a function of an elementary process, namely, the activity of the associative memory ... By associative memory I mean the two following peculiarities of our central nervous system: First, that processes which occur there leave an impression or trace by which they can be reproduced even under different circumstances than those under which they originated.
Page 169 - ... acquired slowly and gradually, as the result of a long continued course of renewed practice. Here too, therefore, the principle of the manifold representation of the bodily organs in the brain is seen in operation. The cerebellum appears to be intended for the direct regulation of voluntary movements by sense impressions. If this hypothesis be correct, it will, accordingly, be the central organ in which the bodily movements incited from the cerebrum are brought into harmony with the position...
Page 94 - The light operates, naturally, on the part of the animal which it reaches. The intensity of the light determines the sense of the response, whether contractile or expansive, and the place of the response, the part of the body stimulated, determines the ultimate orientation of the animal.
Page 131 - The changes toward which the physiological state tends are of two kinds. First the physiological state (like the idea) tends to produce movement. This movement often results in such a change of conditions as destroys the physiological state under consideration. But in case it does not, then the second tendency of the physiological state shows itself. It tends to resolve itself into another and different state.
Page 125 - ... summed up as follows : — (1) No reaction at first: the organism continues its normal activities for a short time. (2) Then a slight reaction by turning into a new position, — a seeming attempt to keep up the normal activities and yet get rid of the stimulation. (3) If this is unsuccessful, we have next a slight interruption of the normal activities, in a momentary reversal of the ciliary current, tending to get rid of the source of stimulation. (4) If the stimulus still persists, the animal...
Page 82 - These tropisms are identical for animals and plants. The explanation of them depends first upon the specific irritability of certain elements of the bodysurface, and, second, upon the relations of symmetry of the body. Symmetrical elements at the surface of the body have the same irritability; unsymmetrical elements have a different irritability. Those nearer the oral pole possess an irritability greater than that of those near the aboral pole. These circumstances force an animal to orient itself...