the entire receptive and centripetal portions of the apparatus concerned in this process. The dental filaments in both the upper and lower jaw, emanating from the structures surrounding, and concerned in, the active capillary and vaso-trophic processes subsidiary to the development of the young teeth, join directly the main trunk of each maxillary nerve, the fibres of each of which, passing through the Gasserian ganglion, unite to form the combined trunk represented as abruptly truncated on the left of this body.

The continuation of the trunk of the sensory portion of the trifacial into the posterior columns of the medulla, which form the floor of the fourth ventricle, is fully illustrated by Fig. 7, from Todd, representing "the central connections of the fifth pair.”

By this direct implantation' the sensory trunk of the trifacial is brought into intimate excitor relations with the three several elements of the cord-so clearly differentiated and distinctly appropriated by Jacobou witsch to motion, sensation, and secretion-thus adapting it, by its actual physical connections with each class of these cells, to become the reflex excitor to any one of these classes of cells or to all of them combined. The mere anatomical and mechanical connection of the sensory fibres of the fifth pair to the medulla oblongata, the admitted teleological relations of the several kinds of cells composing its elements, and the various efferent nervous distributions issuing from its ganglia, all intimately related, as we have said, with efferent fibres of this sensory portion, would indicate plainly the widespread influence it is capable of exercising even had no experimental demonstration been made to give unquestionable verification to the fact. This last convincing evidence has, however, been most satisfactorily and abundantly supplied.

It is scarcely necessary to remark upon this origin here given of the sensory portion of the trigeminus. It is that traced by Dr. Alcock, of Dublin, and given in The Cyclopædia of Anatomy and Physiology as the result of his dissections, and it confirms the statement of Sommering, that it appears to arise almost from the very floor of the fourth ventricle. Erasmus Wilson adopts it, and Herbert Mayo has verified it. Dr. R. B. Todd says (Physiological Anatomy of Brain and Cord): “The ordinary columns are seen distinctly in their ascent to the brain in the floor of the fourth ventricle, as two cylinders [see our Fig. 8, A and F] which form the floor of the fourth ventricle.” It is, perhaps, more properly stated by Alcock, as being beneath the floor of the fourth ventricle. We are thus particular, as the exact relation of its origin to the centric nervous matter has a bearing upon the identity of its behavior, under dental irritation, with the experimental results obtained by Claude Bernard.

Some time in 1852 M. Claude Bernard, of Paris, performed certain experiments to determine the influence of the galvanization of certain nerves upon the secretory functions of various organs. Having abandoned these, he next instituted others, which more recently we find clearly and satisfactorily illustrated in his lectures delivered at the College of France during the sessions of 1854 and 1855, and published in Paris, 1855 and 1856. These brilliant experiments, as we have before said, have won for M. Bernard a well-earned and enduring fame and have done much towards the advancement of physiological science. Begun two years after the publication of our views in regard to the reflex excito-secretory influence of dentition through the fifth nerve on the secretions of the liver, intestines, kidney, and other organs, and not published till fully five years after, they yet afford the most singularly accurate demonstration and verification of their truth in every particular. These experiments consisted in mechanical irritations, applied by means of delicate, pointed instruments, to the nerve-centres and cords in the fourth ventricle at the point, as will be seen, of implantation of the sensory trunk of the fifth nerve. The following description shows how exactly the experimental results, as obtained in the case of animals, correspond with the results attributed some years before to the same source, from the observation of the effect of

1 Leçons de Physiologie Experimentale, etc.

2 The following are our own contributions on Reflex Secretory Action:1st. "The Influence of Dentition in Producing Disease." Read before the Medical Society of Augusta, May 2d, 1850.-Southern Medical and Surgical Journal, June, 1850.

2d. "The Sympathetic Nerve in Reflex Phenomena -A Question of Priority of Announcement with M. Claude Bernard."-Transactions of the American Medical Association, May 5th, 1852, Vol. VI., p. 49.

3d. "A Claim of Priority in the Discovery and Naming of the Excito-Secretory System of Nerves-A Letter to Dr. Marshall Hall, of London," March 2d, 1857.-Southern Medical and Surgical Journal, March, 1857, and London Lancet, May 2d, 1857.

4th. "The Excito-Secretory System of Nerves. Its Relations to Physiology and Pathology."-Prize Essay of the American Medical Association.-Transactions, Vol. X., May, 1857.

5th. "Meckel's Ganglion."-Southern Med. and Surg. Journal, Feb. 1858. 6th. "Classification of Febrile Diseases by the Nervous System."-Transactions of the Amer. Med. Association, Vol. X., 1857.

7th. The Nervous System in Febrile Diseases and the Classification of Fevers by the Nervous System."-Transactions of the Amer. Med. Association, Vol. XI., p. 551, May, 1858.

morbid irritation in the same organs of the child under the influence of dentition.

"We find," says a cotemporary writer,1 "minute details regarding the mode in which Bernard performs his celebrated experiment of inducing artificial diabetes by pricking a certain point of the medulla oblongata either of an herbivorous or a carnivorous animal; but until we read these lectures we were not aware that he had extended his experiment in the manner described in the following paragraph: "When we prick the mesial line of the floor of the fourth ventricle in the exact centre of the space between the origins of the auditory and pneumogastric nerves, we at the same time produce an exaggeration of the hepatic (saccharine) and renal secretions; if the puncture be effected a little higher we very often only produce an augmentation in the quantity of the urine, when this frequently becomes charged with albuminous matters; while if the puncture be

POSTERIOR VIEW OF THE MEDULLA OBLONGATA, WITH MESOCEPHALE AND PART OF CEREBELLUM OF AN INFANT.-S. Pineal gland D. Nates. D'. Testes. ++. Points of emergence of fourth pair of nerves. Y. Posterior pyramids. X. Restiform columns. A, F. Floor of the fourth ventricle, formed by the olivary columus, the fissure between which is the calamus scriptorius. Y'. Posterior surface of mesocephale. B. Valve of Vieussens. N. Anterior surface of crus cerebri. R Corpus dentatum or rhomboideum.

below the indicated point, the discharge of sugar alone is observed, and the urine remains turbid and scanty." Fig. 8, from Foville, exhibits the floor of the fourth ventricle.

It will be seen by examination of Fig. 9, from Bernard, that the

SECTION OF A RABBIT'S HEAD TO SHOW THE DIRECTION OF THE PERFORATION. a. Cerebellum. b. Origin of the seventh pair of nerves. c. Spinal marrow. d. Origin of the pneumogastric nerve. e. Orifice by which the instrument enters the cranium. f. Instrument. g. Fifth pair of nerves. h. Auditory canal. i. Extremity of the instrument reaching the medulla after traversing the cerebellum. Occipital venous sinus. . Tubercula quadrigemina. m. Cerebrum. n. Section

of the atlas.

place indicated for introducing the point i of the piercing instrument f, in order to increase the secretion of urine and to change its character, is very near the implantation of the root of the fifth pair of nerves, g. Hence we may say that this operation illustrates, as perfectly as any artificial measure possibly can, in the irritation produced and the results obtained, the more gradual and permanent effect of this persistent and long-continued dental irritation constantly transmitted during months of vasotrophic excitement, from the peripheral dental filaments through the trigeminal trunk to the floor of the fourth ventricle. This irritation is thence reflected, under the special influence of the ganglionar cells of Jacoubowistch most probably, directly by avenues histologically and functionally congenial, viz., the secretory ganglia and trunk of the splanchnic and finally the distributed branches of the sympathetic, in the coats of the blood vessels and

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among the capillaries-the "vaso-motor nerves"-well named and described by Dr. Brown-Séquard, and "concerning which," in the language of Dr. Austin Flint, Jr., "so much has been written within the past few years."

Cerebro-spinal and Splanchnic Nervous Systems of a Rabbit, showing the nervous connection existing between the liver, lung, and kidney, to explain the production of artificial diabetes, and, by the same rationale, the neuro-dynamic production of uric acid for infantile nuclei.