The brain as an organ of mind . following thereupon. Thisis perfectly true, though only part of the truth. The path taken by stimuli from impressible surfaces to muscles is not generallythe shortest and mostdirect route. In thegreat majority of organ-isms these paths aremore or less bent uponthemselves. Those foringoing impressions mayrun nearly parallel withone another towardssome central situation ;and thence they may bedistributed to muscles invarious parts of thebody—some of thesebeing perhaps not verydistant from the surfacestimulated. In the latter case the track of the stimuluswave is f
The brain as an organ of mind . following thereupon. Thisis perfectly true, though only part of the truth. The path taken by stimuli from impressible surfaces to muscles is not generallythe shortest and mostdirect route. In thegreat majority of organ-isms these paths aremore or less bent uponthemselves. Those foringoing impressions mayrun nearly parallel withone another towardssome central situation ;and thence they may bedistributed to muscles invarious parts of thebody—some of thesebeing perhaps not verydistant from the surfacestimulated. In the latter case the track of the stimuluswave is found to be bent at an acute angle, or the turning point or nerve centre, whence impres-sions are distributed outwards in various directions tomuscles, what are called Nerve Cells become developed. * Since the above was written and in type the observations ofSohiifer (Proceed, of Koy. Soc, January, 1878), and of 0. and ^, have revealed the existence of distinct nerve tissues inseveral species of FiG. Different kinds of Nerve Cells. (Magnificd about 850 diameters.) Chap. I.] OF A NERVOUS SYSTEM. 23 These bodies are interposed so as to constitute part of theactual path of the stimulus wave, and accordingly, theymay be, in effect, junctions for ingoing impressions ordividing stations for out-going impressions. The mattercomposing them seems to be endowed with extreme mole-cular mobility. It is owing to the multitudinous com-binations of these bodies with one another, and withingoing and outgoing fibres, in modes which will besketched in the next chapter, that the complex w^ork ofthe nervous system is enabled to be carried on. Nerve tissue, in the lower forms of animal life, isessentially subservient to the bringing about of move-ments in more or less immediate response to externalshocks or other localized impressions, or of movementsand glandular activity as a result of impressions uponinternal surfaces. These various movements graduallybecome
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