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*Toad, sympathetic nervous system, 113. binocular and stereoscopic, 457. *Trial and error method of learning, 98. method of reacting, 172.
*Watson, J. B. Effect of bearing *Tropism, terminology, 138.
young on rat, 514. *and random movement, 98.
WERNDLY, L. Turning fork-sound etc., theory of, 169.
WERNICKE, C. Work of, 525. * Unic nicellular organisms, reactions of to Weysse, A. W. Animal behavior, 174, electricity, 528.
WOLLENBERG, R. Hypochondria, 540.
WOODWORTH, R. S. and SHERRINGTON, Vagus nerve, action of delphinin on, 72. C. S. A pseudaffective reflex, 74.
Variation, in brain-weight, 467. *Vertebrate, morphology of head of, 175. "YER!
ERKES, R. M. Genetic relations of binocular vision in, 457.
types of action, 132. *spinal nerves in, I.
*Hearing in frog, 279. Vision, and pigment, 174.
Neurology and Psychology
Founded by C. L. Herrick
C. JUDSON HERRICK, Manager,
ROBERT M. YERKES,
HERBERT S. JENNINGS,
University of Pennsylvania
J. MARK BALDWIN, Johns Hopkins Uuiversity
B. F. KINGSBURY, Cornell University
MORGAN, University College, Bristol
Pub ished bi-monthly
The Journal of Comparative
Neurology and Psychology.
PUBLISHER'S ANNOUNCEMENT. Complete sets and separate volumes of back numbers of The JOURNAL OF COMPARATIVE NEUROLOGY (volumes I to XIII) are for sale at this office at the rate of $3.50 per volume unbound, carriage pre-paid. Single numbers are also sold at prices varying with the contents. The new series began with January, 1904. The price of Volume XIV, now complete, is $4.00 (foreign postage 30c extra). The contents of the last issues follows.
Volume XIV, Number 6, November, 1904.
Volume XIV, Number 5, September, 1904.
The Early History of the Olfactory Nerve in Swine. By EDGAR A. BEDFORD. With fourteen figures.
The Relation of the Chorda Tympani to the Visceral Arches in Microtus. By Victor E. EMMEL.
Editorial. Nature Study.
Volume XIV, Number 4, July, 1904.
Editorial. Some Unemphasized Aspects of Comparative Psychology.
Volume XIV, Number 3, Juno, 1904. An Enumeration of the Medullated Nerve Fibers in the Ventral Roots of the Spinal Nerves of Man. By CHARLES E. INGBERT. Thirty-eight figures.
Volume XIV, Number 2, April, 1904.
The Nervous Structures in the Palate of the Frog: the Peripheral Net. works and the Nature of their Cells and Fibers. By C. W. PRENTISS. Twelve figures.
The Beginnings of Social Reaction in Man and Lower Animals. By C. L. HERRICK.
Continued on page three of cover.s
Comparative Neurology and Psychology
ON THE AREAS OF THE AXIS CYLINDER AND
MEDULLARY SHEATH AS SEEN IN CROSS
By HENRY H. DONALDSON and G. W. HOKE.
With one figure.
Introduction. The results presented in this paper are, in each case, based on averages of the measurements of twenty or more spinal nerve fibers. The nerves were taken from various animals representing the five great classes of vertebrates. The measurements show that the areas of the medullary sheath and enclosed axis are nearly equal, and by consequence that the volume of the substance forming the axis cylinders is equal to that forming the medullary sheaths. The relation constitutes a point of similarity remarkable for its wide extension through the vertebrate series. It enables us, moreover, to estimate in any nerve the volume of the substance specialized for the conduction of the nerve impulse. Since this quantitative relation between axis cylinder and sheath is so close, it strongly suggests that in some way the axis controls the formation of the surrounding medullary substance.
In the spinal nerves of some animals this relation, as expressed by the equal areas of the axis and sheath when the fibers are seen in the cross section, was pointed out several years ago
1 The Acrania and Cyclostomi do not develop medullary sheaths on their nerve fibers, and are therefore not included.