. Cunningham's Text-book of anatomy. Anatomy. ELEMENTS OF THE CENTEAL NEKVOUS SYSTEM. 505 non-striated muscle. calated cell (d); and it is customary to distinguish these latter elements (within the central nervous system) as splanchnic efferent cells. It is, however, a matter of fundamental importance to recognise clearly that the real splanchnic efferent cells, the homo- logues of the A B somatic efferent cells, are found in the sympathetic ganglia, and that the elements to which this term is usually applied are in reality inter- calated cells. This account is at variance with the customary d
. Cunningham's Text-book of anatomy. Anatomy. ELEMENTS OF THE CENTEAL NEKVOUS SYSTEM. 505 non-striated muscle. calated cell (d); and it is customary to distinguish these latter elements (within the central nervous system) as splanchnic efferent cells. It is, however, a matter of fundamental importance to recognise clearly that the real splanchnic efferent cells, the homo- logues of the A B somatic efferent cells, are found in the sympathetic ganglia, and that the elements to which this term is usually applied are in reality inter- calated cells. This account is at variance with the customary descrip- tion of the develop- ment of the sym- pathetic system, according to which the cells of the sym- pathetic ganglia are said to be wholly derived from the sen- sory ganglia ; but it offers a reasonable explanation of the facts (i.) that the cells Fig. 445.—Diagram of a Transverse Section through the Left Half of the in the sympathetic Neural Tube representing Two Stages in the Development of the ganglia are of the Efferent Nerves, to suggest the Possible Origin of the Cells of the efferent, and not of Sympathetic Ganglia by migration from the Neural Tube. the sensory, type, and (ii.) that the fibres from the central nervous system establishing relations with them emerge along the motor nerves. Moreover, the information brought to light by recent research in embryology (Froriep, Kuntz, and others) affords positive evidence in support of this view. Elliott, however, opposes this interpretation (Journal of Physiology, 1907, p. 438). Many, if not all, of the sympathetic cells are derived from the walls of the neural tube, and they migrate along the pathways formed by the motor, rather than the sensory, nerves. In the case of the spinal medulla they pass out chiefly along the anterior roots, and from the brain along the motor nerves—the oculo- motor, and the motor divisions of the facial and vagus nerves. Nerve Components.—Erom the statements in the preceding paragraphs i
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