by M. Robin, in a communication made by him to the Académie des Sciences, of Paris, in June, 1847, that the ganglia of the great sympathetic and of the cerebro-spinal nerves enclose the same kind of ganglionary globules, and of elementary tubes, but in different proportions; and hence he does not regard them as separate nervous systems.

Although connected with the brain by the branches of the fifth and sixth pairs of encephalic nerves, and with the spinal cord by the spinal nerves, the sympathetic does not appear to be directly influenced by either; as the functions of the parts to which its ramifications are distributed continue for some time after both brain and spinal marrow have been separated; nay, as in the case of the heart and intestines, after they have been removed from the body. Yet many discussions have been indulged regarding the origin of this important part of the nervous system; some assigning it to the brain, others to the spinal marrow, whilst others again esteem it a distinct nerve, communicating with the brain and spinal cord, but not originating from either; receiving, according to M. Broussais,1 by the cerebral nerves, the excitant influence, and applying it to movements that are independent of the centre of perception. In like manner, he affirms, when irritation predominates in the viscera, it is conveyed by the ganglionic to the cerebral nerves, which transmit it to the brain. Reil and Bichat, esteeming the sympathetic to be the great nervous centre of involuntary functions, have termed it the organic nervous system, in contradistinction to the animal nervous system, which presides over the animal functions; whilst Lobstein, who has published an ex professo work on the subject, assigns three functions to it. 1. To preside over nutrition, secretion, the action of the heart, and the circulation of the blood; 2. To maintain a communication between different organs of the body; and 3. To be the connecting medium between the brain and abdominal viscera. Remak,3 who believes that the animal economy possesses two sensoriums,-the one in the cerebro-spinal axis, the other in the ganglionic system,considers, that as in the cerebro-spinal system of nerves two orders of phenomena occur,-the perception of sensation, and the reaction or reflection of volition; so, in the organic nervous system, two analogous actions take place, organic perception, or, as it has been called, Hallerian irritability, and reaction or organic reflection, as shown by J. Müller.

2

From the result of his own researches, Dr. Carpenter' inferred, that the sympathetic system does not exist in the lowest classes of animals in a distinct form;-that the nervous system of the invertebrata, taken as a whole, bears no analogy to it, and that as the divisions of this become more specialized, some appearance of a separate sympathetic

'A Treatise on Physiology applied to Pathology, translated by Drs. John Bell, and R. La Roche, p. 257, Philad., 1832.

249.

'De Nervi Sympath. Human., &c., translated by Dr. Pancoast, Philadelphia, 1831. Ammon's Monatschrift, June, 1840; and Edinb. Med. and Surg. Journal, Jan., 1841, p. Elements of Physiology, by Baly, i. 736, Lond., 1838. Dissertation on the Physiological Inferences to be deduced from the Structure of the Nervous System in the Invertebrated Classes of Animals, Edinb., 1839; reprinted in Dunglison's Med. Library, Philad., 1839; also, his Principles of Human Physiology, p. 111, London, 1842.

presents itself, but it is never so distinct as in the vertebrata; hence he deduces, and with probability, that as the sympathetic system is not developed in proportion to the predominant activity of the functions of organic life, but in proportion to the developement of the higher division of the nervous system, its office is not to preside over the former, but to bring them in relation with the latter; so that the actions of the organs of vegetative life are not dependent upon it, but influenced by it in accordance with the operations of the system of animal life.

Again, the great sympathetic has been esteemed to be the visceral nerve par excellence, or the one that supplies the different viscera with their nervous influence,—a part of its office as the nervous system of involuntary functions. On examining the course of the great sympathetic, we find many filaments proceeding from the cervical and thoracic ganglions, interlacing and forming the cardiac plexus, from which the nerves of the heart and great vessels arise. The same thoracic ganglions furnish a branch to each intercostal artery. A nerve of the great sympathetic-called the great splanchnic or visceral-proceeding from some of the thoracic ganglions, passes through the pillars of the diaphragm into the abdomen, and terminates in the large plexus or ganglion, called the semilunar; and this by uniting with its fellow of the opposite side, constitutes the still more extensive interlacing,-the solar plexus. From this, numerous filaments proceed, which-by accompanying the coronaria ventriculi, hepatic, splenic, spermatic, renal, superior and inferior mesenteric, and hypogastric arteries-are distributed to the parts supplied with blood by these arteries, the stomach, liver, spleen, testes, kidneys, intestines, &c. Weber, however, who examined the great sympathetic in different animals, affirms, that the splanchnic may not be the sole visceral nerve, but that the eighth pair may share in the function. He states, that the great sympathetic is less developed, the lower the animal is in the scale; whilst the eighth pair is more and more developed as we descend, and at length is the only visceral nerve in some of the mollusca. Sir A. Cooper's' experiments satisfied him, that this nerve is essential to the digestive process; but of this we shall have to speak hereafter. In the prosecution of those experiments, he found, that when the great sympathetic was tied on a dog, but little effect was produced: the animal's heart appeared to beat more quickly and feebly than usual; but of this circumstance he could not be positive, on account of the natural quickness of its action. The animal was kept seven days, at which time one nerve was ulcerated through, and the other nearly so, at the situation of the ligatures. Another animal on which the sympathetic had been tied nearly a month before, was still living when he wrote. When the pneumogastric or eighth pair, the phrenic, and the great sympathetic were all tied on each side, "the animal lived little more than a quarter of an hour, and died of dyspnoea.

These experiments would appear to show, either that the great sympathetic is not so indispensable to the economy as has been imagined;

1

1 Anatom. Comparat. Nerv. Sympath., Lips., 1817.

2

Guy's Hospital Reports, vol. i. p. 457, London, 1836.

3 Ibid., p. 471.

or that it is, in every part, a generator of nervous influence, so that if its connexion with the brain or any other viscus be destroyed, the divided portions may still possess the power of generating nervous agency. But if we admit this as regards the system of the great sympathetic, we shall find, that it is difficult to extend it to detached portions of the nervous system of animal life.

It must be confessed, that our knowledge of the uses of this great division of the nervous system is far from being precise; for whilst some physiologists believe it to be concerned in every involuntary and organic action; Dr. Proctor' thinks, that the nearest approach to a positive determination of its use that we can arrive at with our present limited knowledge is, that "it is for the purpose of regulating the tonic contraction of the arterial system, and for nothing else." One distinguished observer, M. Magendie,' inquires whether we have sufficient reason for the belief, that it is a nerve at all! and a writers of distinction, Dr. J. C. B. Williams, admits, that nothing is definitely known as to the properties communicated by ganglionic nerves; and he adds, "Before the influence of the ganglionic system can be employed as an element in pathology, its existence must be proved, and its properties defined in physiology: this has not been done."

According to the experiments of M. Flourens, the semilunar is the only ganglion that exhibits any great sensibility; and hence it has been considered as a sort of intervention to connect the viscera with the encephalon.

M. Lepelletier thinks we are justified in dividing the nerves into five classes: the first, comprising the nerves of special sensibility,—the olfactory, optic, lingual branch of the fifth pair, and auditory:-the second, the nerves of general sensibility, the fifth pair; and the spinal nerves, through their posterior root:-the third, comprising the voluntary motors; the spinal nerves, by their anterior roots, the motores oculorum or common oculo-muscular, the external oculo-muscular, and the hypoglossal:-the fourth, instinctive motors, involuntary, respiratory nerves of Sir Charles Bell, the pathetic, facial, glosso-pharyngeal, pneumogastric, and spinal accessory; and the fifth, nerves of vital association and nutrition-the filaments and plexuses of the ganglionic system. Dr. Fletcher adopts a different arrangement. He divides them into ganglionic and cerebro-spinal; the latter being subdivided into the respiratory, motiferous, sensiferous, and regular; the last including those which communicate both the faculty of sensibility and the stimulus of volition.

'Medico-Chirurg. Rev., Jan., 1845, p. 182.

* Précis de Physiologie, 2de édit., i. 171. Paris, 1825.

3 Principles of Medicine, 3d Amer. edit., by Dr. Clymer, p. 200, note, Philad., 1848.

4 Recherches Expérimentales sur les Propriétés et les Fonctions du Système Nerveux, &c., 2d édit., p. 229, Paris, 1842.

5 Traité de Physiologie Médicale et Philosophique, iii. 250, Paris, 1832.

6 Rudiments of Physiology, P. ii. a. p. 71, Edinb., 1836.

5. True Spinal, Excito-Motory or Reflex Nervous System.-Dr. Marshall Hall1 has proposed another division of the nervous system, which is calculated to explain many of the anomalous circumstances we so frequently witness. He proposes to divide all the nerves into

1. The cerebral or sentient and voluntary.

2. The true spinal or excito-motory.

3. The ganglionic or nutrient and secretory.

If the sentient and voluntary functions be destroyed by a blow on the head, the sphincter muscles still contract when irritated, because the irritation is conveyed to the spine, and the reflex action takes place to the muscle so as to throw it into contraction. But if the spinal marrow be now destroyed, the sphincters remain entirely motionless; because the centre of the system is destroyed. Dr. Hall thinks, that a peculiar set of nerves constitute, with the true spinal marrow as their axis, the second subdivision of the nervous system; and as those of the first subdivision are distinguished into sentient and voluntary, these may be distinguished into excitor and motory. The first, or excitor nerves, pursue their course principally from internal surfaces, characterized by peculiar excitabilities, to the vesicular centre of the medulla oblongata and medulla spinalis; the second or motor nerves pursue a reflex course from the medulla to the muscles, having peculiar actions concerned principally in ingestion and egestion. The motions connected with the first or cerebral subdivision are sometimes-indeed frequently-spontaneous; those connected with the true spinal are, he believes, always excited. Dr. Hall thinks that there is good reason for viewing the fifth, and posterior spinal nerves as constituting an external ganglionic system for the nutrition of the external organs; and he proposes to divide the ganglionic subdivision of the nervous system into 1, the internal ganglionic, which includes that usually denominated the sympathetic, and probably filaments of the pneumogastric; and 2, the external ganglionic, embracing the fifth and posterior spinal To the cerebral system he assigns all diseases of sensation, perception, judgment, and volition,-therefore all painful, mental, and comatose, and some paralytic diseases. To the true spinal or excito

nerves.

'Lectures on the Nervous System, London, 1836, and American edit, Philad., 1836. Also, his Lectures on the Theory and Practice of Medicine, in the London Lancet for Feb. 3, and Feb. 7, 1838.

VOL. I.-7

motory system belong all spasmodic and certain paralytic diseases. He adds, that these two parts of the nervous system influence each other both in health and disease, as they both influence the ganglionic system.1

2

3

The views of Dr. Hall on the excito-motory function have been embraced by Müller, Grainger, Carpenter, and indeed, with more or less modification, by almost all physiologists. Dr. Carpenter inferred from his inquiries, that the actions most universally performed by a nervous system are those connected with the introduction of food into the digestive cavity, and that we have reason to regard this class of actions as every where independent of volition, and perhaps also of sensation, -the propulsion of food along the oesophagus, in man, being of this character;-that for the performance of any action of this nature, a nervous circle is requisite, consisting of an afferent nerve, on the peripheral extremities of which an impression is made,-a ganglionic centre, where the white fibres of which that nerve consists terminate in gray matter, and those of the efferent nerve originate in like manner; and an efferent trunk conducting to the contractile structure the motor impulse, which originates in some change between the gray and white matter; that in the lowest animals such actions constitute nearly the entire function of the nervous system, the amount of those involving sensation and volition being very small; but as we ascend the scale, the evidence of the participation of true sensation in the actions necessary for acquiring food, as shown by the developement of special sensory organs, is much greater; but that the movements immediately concerned with the introduction of food into the stomach remain under the control of a separate system of nerves and ganglia, to the action of which the influence of the cephalic ganglia-the special if not the only seat of sensibility and volition-is not essential; that, in like manner, the active movements of respiration are controlled by a separate system of nerves and ganglia, and are not dependent upon that of sensation and volition, although capable of being influenced by it ;— that whilst the actions of these systems are, in the lower tribes, almost entirely of a simply reflex character, we find them, as we ascend, gradually becoming subordinate to the will; and that this is effected by the mixture of fibres proceeding directly from the cephalic ganglia with those arising from their own centres ;-that the locomotive organs, in like manner, have their own centres of reflex action, which are independent of the influence of volition, perhaps also of sensation;-that the influence of the will is conveyed to them by separate nervous fibres, proceeding from the cephalic ganglia, and that similar fibres probably convey to the cephalic ganglia the impressions destined to produce sen

1

Principles of the Theory and Practice of Medicine, by Marshall Hall, M. D., F. R. S., p. 243, London, 1837, and American edit. by Drs. Bigelow and Holmes, Bost., 1839.

' Handbuch der Physiologie, s. 333, and s. 688, Coblenz, 1835, 1837, or the English translation by Dr. Baly, i. 707, London, 1838.

3 On the Structure and Functions of the Spinal Cord, London, 1837.

4 Op. cit.

5 Todd and Bowman, the Physiological Anatomy and Physiology of Man, p. 312. London,