of these two opinions; either one of them can only rationally explain the phenomena by invoking the aid of the excito-secretory action originated by the irritation caused in the branches of the trifacial during the evolution of the teeth.

The urinary secretion is much influenced throughout the period of dentition. "Hunter,' and afterwards Underwood," says Dr. Laycock,3 3 "remarked the connection between the teeth and the kidney and bladder in children; the growth of the former being accompanied with increased flow of urine, symptoms of gonorrhoea, and of stone in the bladder, and involuntary micturition. Mr. Bingham corroborates these observations," &c. At an early period. of our connection with the study of medicine, we were led to investigate the relation which the process of dentition bore to this particular set of concomitants, and in the consideration of these relations were first traced out those connections between the cerebro-spinal excitor nerves and the ganglionic secretory nerves which constitute the basis of the excito-secretory function in every portion of the organism. Our observation, then, led us to the opinion that this increase of renal secretion was caused by reflected peripheral irritation from the growing teeth upon the dental branches of the fifth pair, which irritation being transmitted to the spinal centre giving origin to this sensitive nerve, rendered it an excitor to the secretion of the kidneys through the ganglionic system presiding over that particular function. A more thorough investigation of the anatomical relations of the trifacial, and especially of its final central connection with the cerebro-spinal axis, have only served to strengthen the above convictions, and while placing our observed facts in philosophical relation with some of the recent experiments of M. Claude Bernard, of Paris, we are more fully convinced of their significance. Dr. Alcock' thus traces the trunk of the trifacial from the surface of the crus cerebelli to its real origin: "The course of the larger packet" (which is the sensitive) "is also beneath and before that of the lesser, and hence in the usual mode of dissection, in which the brain is reversed, it presents itself first.

1 The Natural History of the Human Teeth, p. 234.

2 On Diseases of Children. Ninth edition, edited by Dr. Marshall Hall; p. 252. London, 1835.

3 Essay on Hysteria, p. 86, American edition. Philadelphia, 1840.

4 Vide Leçons de Physiologie. Paris, 1854 and 1855.

5 Cyclopedia of Anatomy and Physiology, vol. xi. p. 271, art. Fifth Pair of Nerves.

Its direction is backwards, downwards, and inwards, towards the upper extremity of the spinal bulb; .... it is then situate in the angle formed by the three peduncles of the cerebellum at their junction with the hemisphere; behind the middle, beneath the superior, and above the inferior, and before—or in common language, beneath the floor of the fourth ventricle." He further quotes Somerring,' that "it appears to arise almost from the very floor of the fourth ventricle." The following lignograph, No. 140 Todd's Cyclopedia of Anatomy and Physiology, will more fully illustrate the central connection of the fifth pair.

LATERAL VIEW OF THE PONS, SPINAL BULB, AND COURSE OF THE FIFTH NERVE IN MAS.-1. Pons Varolii. 2 Spinal bulb. 3. Olivary body. 4. Spinal cord. 5. Superior peduncle of cerebellum. 6. Cut surfaces of middle cerebellum. 7. Inferior peduncle of cerebellum. 8. Cut surface of crus cerebri. 9. Ganglion of fifth nerve reversed. 10. Ganglionic portion of the nerve. 11. Non-ganglionic portion of fifth nerve. 11'. Roots of non-ganglionic portion. 12. Eminence at the insertion of both portions of the fifth nerve. 13 Fasciculus to anterior column of spinal cord. 14. Fasciculus to posterior column. 15. Auditory nerve. 16. Portio dura. 17. Posterior roots of superior cervical nerves.

2

"I have adopted," says Erasmus Wilson, "the origin of this nerve given by Dr. Alcock, of Dublin, in the Cyclopedia of Anatomy

De Corpori Humani Fabrica. 1798.

2 Dissector's Manual of Practical and Surgical Anatomy. Second edition. London, 1853. P. 341, note.

and Physiology, as the result of his dissections. Mr. Mayo also traces the anterior root of the nerve to a similar origin."

We also here adduce the high authority of Dr. R. B. Todd' in relation to the connection of the trifacial with the floor of the fourth ventricle. "The ordinary columns are seen distinctly in their ascent to the brain in the fourth ventricle, as two cylinders (A, F, Fig. 4), which form the floor of that cavity. . . . . We here see distinctly that these columns" (which form the floor of the fourth ventricle) "are the source of origin of these nerves (the seventh pair), and no doubt they are equally so of all the nerves which are connected with the medulla oblongata, namely, the fifth pair, the eighth, the ninth, and probably also the sixth." The cut used by him is taken from Foville, and we here introduce it.

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 columns, 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.

Some time in 1852 (so far as we can ascertain by reference to records at hand), Mons. C. Bernard, of Paris, performed certain

Descriptive and Physiological Anatomy of the Brain and Spinal Cord and Ganglions, &c., p. 177. London, 1845.

VOL. X.-33

experiments to determine the influence of the galvanism 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, Paris, 1855 and 1856.1 These brilliant experiments have won for M. Bernard a well-earned and enduring fame, and have done much towards the advancement of physiological science.

"We find," says a recent writer," "as might be expected, 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 a 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 of the 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 below the indicated point, the discharge of sugar alone is observed, and the urine remains turbid and scanty. Hence it appears that we may distinguish two points, of which the inferior corresponds to the secretion of the liver, and the superior to that of the kidneys. As, however, these two points are very near to each other, it often happens that, if the instrument enters obliquely, they are simultaneously wounded, and the animal's urine not only becomes superabundant, but, at the same time, saccharine.'" We here copy a cut from Bernard, showing the relation of the parts, and the point of pricking the floor of the fourth ventricle.

It will be seen, by examination of the above figure, that the 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 to the implantation of the root of the fifth pair of nerves, g, in the following figure. Hence, we may fairly say that the above operation, performed, as it appears from

1 Leçons de Physiologie Expérimentale, &c.

British and Foreign Medico-Chirurgical Review, No. xxxvii., Jan., 1857, p. 32

M. Claude Bernard's work,' on the 13th of February, 1855, proves experimentally that irritation made in a spinal centre is competent

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. 6. 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. k. Occipital venous sinus. 1. Tubercula quadrigemina. m. Cerebrum. n. Section of the atlas.

to excite and to modify the secretory function of the abdominal viscera, which function is exercised under the reign of the ganglionic system, the parts in which it goes on being only intermediately connected with that spinal centre thus irritated. This fact, thus proved in experiment by M. Claude Bernard, the records. of American medicine will show, was recognized and announced from observation in June, 1850. In M. Bernard's experimental investigation, the irritation was applied directly to the nervous centre; in the induction from observation, peripheral irritation through the dental branches of the fifth nerve was recognized as competent to excite the secretion, and modify the products of secretion. The observation here, and not the more recent experiment, was the real parent of the principle of excito-secretion. The conclusion arrived at, from the observation of pathological phenomena, em

1 Op. citat., p. 288.

2 Southern Medical and Surgical Journal, vol. vi. p. 321.