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Elements of physiological psychology (1887)
Elements of physiological psychology - 1887 Author:George Trumbull Ladd Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: EXAMPLES OF REFLEX ACTION. 19 tion," so far as it concerns the different and distant parts of the body, might be illustrated in many ways. Inasmuch as the pla... more »nt is an organism, there is a reciprocal dependence of the structure and action of all its parts. But each part of the plant acts directly arid slowly on only contiguous parts in effecting the distribution of the fluids, upon the spread of which the life and growth of the plant depend. In the case of the animal, however, an effect produced in one part of the body may quickly spread to other distant parts by the mediation of the nervous system. The circulation of the blood is made to affect, and to be affected by, the state of the skin and the muscles, the state of the respiratory organs, or the state of the mind's feeling as determined by the ideas before the mind. A draught of cold air, for example, strikes some peripheral portion of the body ; the heart and lungs modify their activities, the muscles contract, and a shudder runs through the physical framework ; the secretions are disturbed, and the mind is, perhaps, seized with a vague feeling of fear. Such a complex effect of the stimulus of cold on some region of the skin has been brought about by the action of the nervous system, with its peripheral end-organs, conducting nerve-fibres, and nervous centres. Or, again, the seeing of some sight or the hearing of some sound is followed by ideas and emotions of shame, or of fear, or of joy. A complex co-ordination of the muscles then takes place, so as to move the limbs in running, to give or ward off a blow, to extend the hand in greeting, to lift up or bow down the head. In this case, also, the action of heart and lungs and secretory organs is greatly modified ; the capillary circulation is altered, and the cheeks are bla...« less