8. Ueber die Sensorischen Functionen des Rückenmarks.
On the Sensorial Functions of the Spinal Cord. By E. PFLÜGER.
9. Ueber die Gekreuzten Wirkungen des Rückenmarks. Von A. VON BEZOLD. (Zeitschr. für wissensch. Zoologie,' ix.
MEISSNER'S Bericht,' 1858.)
On the Crossed Actions of the Spinal Cord. By A. VON BEZOLD.
10. Course of Lectures on the Physiology and Pathology of the Central Nervous System. By C. E. BROWN-SÉQUARD, M.D. 1860. Also in Journal de Physiologie.'
THE difficulties met with in the study of the structure and functions of the central nervous organs depend chiefly on the great complexity of their organization. To the anatomist, the softness and delicacy of the component elements obstruct and render difficult microscopic elucidation, whilst the physiologist studying the results of vivisections on animals has to contend with, 1st, the difficulty of ascertaining phenomena in themselves subjective; and 2ndly, in instances when this is no obstacle, and in which the results are sufficiently objective, he has still the difficulty of being able to divide or to irritate one part without at the same time operating on others. Remembering these things, it will not appear strange that, in reference to the structure and functions of the spinal cord, opposite and conflicting opinions should still be entertained.
In regard to the method of investigating structure, there is but one plan which, with more or less modification of detail, is now generally adopted. This consists in hardening the organ by chromic acid, or alcohol, so that thin sections can be made, which may be rendered transparent by turpentine, chloride of calcium, &c. By maceration in carmine, observation may in some points be facilitated. By the study of many hundreds of such preparations, something like a general plan of the structure of this complex organ may be arrived at.
We feel that to enter into an account of anatomical details would only perplex and weary the general reader; but an idea of the plan or type of structure to which these details lead cannot fail to interest the most practical mind, since some conception of structure is essential to an understanding of healthy and diseased function.
In histological language, the spinal cord may be defined as a reticulated column of connective-tissue, containing in its substance bloodvessels, and in its meshes nerve-fibres and nerve-cells. It consists, in fact, of nervous and non-nervous elements, the latter being subservient and secondary to the former.
It is only quite recently that anatomists have recognised the existence of a considerable amount of connective-tissue in the spinal cord, and here as everywhere we owe much to the researches of Virchow. Although Keuffel, in the year 1811, demonstrated by a sort of maceration of the cord that a framework of connective-tissue permeated every part, subsequent investigators (Henle, Stilling, Arnold, Gerlach, Köl