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them occurs that multiplication of fibres, necessary to the enormous expansion of the white matter of the hemispheres. Two of these bodies are usually named together, the corpora striata and thalami optici, as being closely conjoined in the heart of the white substance of the hemispheres; through them most of the ascending fibres of the main stem spread out into the hemispheres. They contain a large amount of grey matter. A third mass, the corpora quadrigemina, or quadruple bodies, is more detached, and lies behind, between the cerebrum and the cerebellum. This centre is closely connected with the optic nerve, and has important functions relating to vision. In the lower vertebrata (as fishes), it assumes very large proportions as compared with the rest of the brain. Resting on the middle cleft of the four eminences, is a small conical body, called the pineal gland, curious as being supposed, by Descartes, to be the seat of the soul.

The functions of the Hemispheres of the Brain, including the enclosed Ganglia, comprehend all, or nearly all, that is comprised in mind. When they are destroyed, or seriously injured, sensation, emotion, volition, and intelligence are suspended. Movements are still possible, but there is no evidence that they are accompanied with consciousness, in other words, with feeling and intelligence; they are without purpose, or volition.

It would be interesting, if we could assign distinct mental functions to different parts of this large and complicated organ; if we could find certain convolutions related to specific feelings, or to specific intellectual gifts and acquirements. This Phrenology attempted, but with doubtful success. Yet, it is most reasonable to suppose that, the brain being constituted on a uniform plan, the same parts serve the same functions in different individuals.

The Cerebellum, little brain, or after-brain, lies behind and beneath the convoluted hemispheres. It is a nearly wedgeshaped body, divided into two halves, with connecting white matter. Like the hemispheres, its outer surface is a thin cake of grey matter, extended, not by the convoluted arrangement, but by being folded into plates or laminæ. The connexions of the cerebellum are, beneath, with a detached branch of the great stem, and above with the hemispheres, through the corpora quadrigemina; the two halves are united laterally by the pons varolii.

The functions of the Cerebellum are still under discussion. Certain experiments, made by Flourens, were interpreted as

FUNCTIONS OF THE CEREBELLUM.

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showing that it is the centre of rhythmical and combined movements, such as the locomotive movements-walking, flying, swimming, &c. Its destruction in pigeons took away the power of standing, flying, walking, leaping, without seeming to destroy the cardinal functions of the mind, the powers of sensation and volition. The inference has been denied by Brown-Séquard, who affirms that the same inability of guiding and combining the movements follows the destruction or irritation of other parts of the base of the brain. The two sets of observations are not inconsistent; for, as the nervous action has to traverse a certain course or circuit, it may be suspended by destroying any part of the line. What seems to be established by the observations is, that there is a separate locality concerned in joining movements into harmonious or combined groups for executing the voluntary determinations.

THE NERVES.

5. The nerves are the branching or ramifying cords, proceeding from the centres, and distributed to all parts of the body.

They have been locally divided into spinal and cerebral, according as they emerge from the Spinal Cord, or directly from the Brain. This is chiefly a matter of local convenience; those nerves supplying the head and face, emerge at once from the brain, through openings in the skull; the rest descend in the spinal cord, and are given off, at openings between the vertebræ, higher or lower, according to their ultimate destination.

The mode of emergence from the spinal cord is peculiar. At the interstices of the vertebræ, a couple of branches emerge, for the two sides of the body. Each member of the couple is composed of two portions, or roots, an anterior and a posterior root, which at a little distance unite in a common stem. It is observed, however, that the posterior root has a little swelling or ganglion, containing grey substance, there being nothing to correspond in the anterior root.

6. The general function of the nerves is to transmit influence from one part of the system to another.

The nerves are supposed to originate nothing; they are exclusively employed in carrying or conveying energy of

their own kind. In the final result, this energy stimulates muscles into action, and without it no muscle ever operates. But in the circles of thought, a great many nerve currents go their rounds, without stimulating muscles.

7. The circuit of nervous action supposes two classes of nerves, the incarrying and the outcarrying. These are usually combined in the same trunk nerve. They appear in separation, in the double roots of the spinal nerves.

The nervous influence does not proceed indiscriminately to and fro, in the same fibres; one class is employed for couveying influence inwards, in sensation, and the other class for conveying influence outwards, in volition. At the emergence of the spinal nerves, the classes are distinct. It was the discovery of Bell, that the posterior roots, distinguished by the little ganglionic swellings, are nerves purely of sensation; the anterior roots, nerves purely of movement. It would be a point of great interest, if these pure nerves could be traced upwards into the nerve centres, so as to show which centres received sensory fibres, and which motory; this would be the first clue to a genuine Phrenology.

The Cerebral Nerves are nearly all pure nerves. They were formerly divided into nine pairs, but there are, in reality, twelve pairs.

The first pair is the olfactory, or nerve of Smell. The second is the optic, or nerve of Sight. The third, fourth, and sixth pairs are distributed to the muscles of the eye, and therefore determine its movements. The fifth pair is double, containing a motor branch to the muscles of the jaws, and a sensory branch connected with the sensibility of the face, and containing the nerve of Taste. The seventh pair is motor, and supplies the muscles of the face. The eighth is the nerve of Hearing. The ninth supplies sensory fibres to the tongue and throat (being a second nerve of Taste), and motor fibres to the muscles of the throat or pharynx. The tenth, called pneumo-gastric, supplies the larynx, the lungs, the liver, and the stomach, and is the medium of a large amount of sensibility. The eleventh, called spinal accessory, is motor. twelfth pair (hypo-glossal) is the motor nerve of the tongue.

The

BOOK I.

MOVEMENT, SENSE, AND INSTINCT.

CHAPTER I.

MOVEMENT, AND THE MUSCULAR FEELINGS.

1. THE Muscular Feelings agree with the sensations of the senses in being primary sources of feeling and of knowledge, localized in a peculiar set of organs; their characteristic difference is summed up in the consciousness of active energy.

The most fundamental contrast existing among the feelings of the human mind, is the contrast of Active and Passive. The exercise of rowing a boat gives a feeling of activity or energy; in a warm bath, the consciousness is of the passive kind. The contrast would appear to be embodied in the nervous system; the outcarrying nerves, together with the nerve centres whence they immediately proceed, being associated with the feelings of activity; the incarrying nerves and their allied centres with sensation or passivity.

Not only should the muscular feelings form a class apart from the sensations, on the ground now stated, but it is farther believed that their consideration should precede the account of the senses. The reasons are- that movement precedes sensation, and is at the outset independent of any stimulus from without; and that action is a more intimate and inseparable property of our constitution than any of our sensations, and in fact enters as a component part into every one of the senses, giving them the character of compounds, while itself is a simple and elementary property.

Of the Muscular System.-The movements of the body are performed by means of the substance called muscle, or flesh: a sub

stance composed of very fine fibres, collected into separate masses, of great variety of form, each mass being a muscle. The peculiar property of the muscular substance is contractility, or the forcible shrinking of the fibres under a stimulus, whereby the muscle is shortened, and the attached bones drawn together in consequence. As an example, we may mention the muscle of the calf of the leg, a broad round mass of flesh, ending above and below in the strong white fibrous substance, known as tendon, by which it is connected with the bones; the upper tendon with the bone of the leg, the lower with the heel; its contraction draws the heel towards the leg, straightening the line of leg and foot, and thus compelling the body to rise.

The ultimate fibres of the muscles, the fibrils or fibrilla (less than the ten-thousandth of an inch in diameter), are found to consist of rows of rectangular particles; in the contraction of the muscle, these particles become shorter and thicker. The fibrils are made into bundles, about 3 of an inch in thickness, called fibres; and the fibres are made up into larger bundles, or threads, which are visible to the eye, as the strings composing flesh.

The contraction of the muscle requires the agency of the nerves, distributed copiously to the fibres. A farther condition of contractile power is a supply of arterial blood. The oxidation of the substances found in the blood is the ultimate source of muscular power; the oxygen, taken into the lungs, and the food, taken into the stomach, are the raw material of all the forces of the system.

2. For the most part, our movements are stimulated through our senses, as when a flash of light or a loud sound makes us start; but it is a fact of great importance, that movements arise without the stimulation of sensible objects, through some energy of the nerve centres themselves, or some stimulus purely internal. This may be called the Spontaneous Activity of the system.

Spontaneous Activity is the explanation of many appearances, and is an essential element of the will, on the theory maintained in this work. The following facts are adduced as both proving and illustrating the doctrine :

:

(1) The muscles never undergo an entire relaxation during life. Even in profound slumber, they possess a certain degree of tension, or rigidity. This state is called their 'tonicity,' or tonic contraction. It is excited through the medium of the nerves. The cutting of the nerves, or the destruction of the nerve centres, renders the muscles flaccid. The inference is, that at all times a stream of nervous energy flows to the muscles, irrespective of stimulation from without.

(2) The permanent closure of the muscles called sphinc

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