whole brain seems to be a particular portion of the central organ, or medulla oblongata. While this remains entire the animal retains its sensibility, breathes, and performs instinctive motions. But if this small mass of the nervous system be injured, there is an end of the animal functions, and death ensues."1

Müller says, "An animal in which the cerebral hemispheres have been removed, no longer reasons; but, nevertheless, it feels." 2

The functions or operations of the brain, are produced in a different manner from other functions in the animal economy, and are governed by different laws.

The brain having the function of consciousness, not only derives intelligence from external objects, which it does through the senses, (which in itself is a peculiarity;) but independently of them, and by reflection the brain obtains intelligence, ideas, thoughts, and imaginations from its own internal operations and impressions, which is consciousness; and communicates them to be acted upon through the functions of volition and of the will; and it directs and guides its own elaborations, and can compare and reflect upon both internal and external impressions, derived through the senses, at the command of the will: and which latter, is what Locke defines to be intellectual liberty.

And the brain also derives impressions, ideas, and sensations, through the nerves of animal and oragnic life; since consciousness is manifested, when the special senses are lost or suspended, either from injury or disease; and Sir B. Brodie says, that "consciousness may be influenced by physical impressions of various kinds, communicated from

1 Brodie's Enquiries,' pp. 46, 47.

2 Müller's Physiology,' v. i, pp. 826.

other parts of the corporeal system, through the medium of the nerves; not as the immediate result of impressions on the external senses, or of anything that was passing on the mind previously."1 Thus, while intellect is peculiar to the cerebrum, the posterior lobe of which is peculiar to man and to higher intellect only, Brodie says, "the medulla oblongata, cerebellum, thalami, corpora striata, and tubercula quadrigemina are connected with that class of phenomena which belong to the animal appetites, and instincts."2

Again, "The cerebellum belongs more especially to what Bichat has called organic life, and furnishes the nervous force required for the action of the heart, respiration, digestion, and the other more corporeal functions. It is also the part principally connected with the animal instincts (instinctus mere naturales), and the emotions; but not exclusively, as the other bodies situated in the base of the brain belong to the instincts and emotions also." Flourens and Hertwig consider the cerebellum subservient to the "coordination of muscular action." The experiments of M. Flourens are more lucid and more decisive in their results. "He found that the animals evinced no signs of sensibility in the cerebellum while it was being removed. He extirpated the cerebellum in birds by successive layers; but their sight and hearing were perfect; Volition, sensation, and memory, therefore, were not lost, but merely the faculty of combining the actions of the muscles in groups, and the endeavours of the animal to maintain its equilibrium were like those of a drunken man."4

1 Brodie's 'Enquiries,' p. 70.

2 Ibid., p. 176.

3 Ibid., Notes, p. 264.

Müller's Physiology,' v. i, p. 830*.

The medulla oblongata, is ancillary to the manifestation of the functions of the cerebral hemispheres; it being the seat of the faculty of sensation, motion, and volition. It concentrates the senses for the use of the brain, and becomes co-ordinate, in the development and performance of the functions of the cerebral hemispheres.

The medulla oblongata is the seat of volition, as well as of motion and sensation. Volition is distinguished from will, which latter is intellectual, and is derived from the hemispheres, and is supposed to be seated in the grey substance, or vesicular neurine of the convolutions.

The medulla oblongata.—“It is the seat of volition; the experiments of M. Flourens show, that animals in which the cerebral hemispheres have been removed, though in a state of stupor, are still capable of executing voluntary movements; and they have still the power of volition after the removal of the cerebellum also; but by this last mutilation, their movements are deprived of force and co-ordination. The medulla oblongata is the seat of the faculty of sensation ;—this is not merely shown by the anatomical fact that all the cerebral nerves, with the exception of the first and second, are connected with it, or with its prolongations in the brain.

From the researches of Magendie and Desmoulins it results that the removal of the cerebral hemispheres and the cerebellum, does not deprive an animal of the power of sensation. The central organs of the senses of sight and smell are lost with the cerebral hemispheres, and blindness The animal has doubtless lost its memory, ensues; it no longer reasons, but nevertheless it feels, and the sensations excite in it movements which are different from the phenomena of mere nervous reflection. Cuvier very aptly

compares animals in this condition to a sleeping man; he also seeks an easy position; he feels.” 1

The nerves of sensation, all but the first and second pairs, are derived from the medulla oblongata, or from its prolongations in the brain, and are carried to the hemispheres through the commissures. Müller says, "Some have believed that the medulla oblongata is the central organ for all sensations. This appears to me to be an error, if by medulla oblongata be meant only the superior enlarged portion of the spinal cord, and not its prolongations into the cerebrum.” 2

"The capacity of the mind in different animals manifestly increases pari passu, with the extension of the surface of the cerebral convolutions." Sir B. Brodie says, "The surface of the hemispheres is formed into folds, or convolutions, and as the fissures by which they are separated are deeper, and more numerous, so does the grey, bear a larger proportion to the medullary substance." 4 And again, "The nervous force is supposed to be generated in the grey, or vesicular substance, of which the greater part is expanded on the surface of the cerebral hemispheres, the extent of that surface depending not so much upon the bulk of the entire brain as on the number and depth of the convolutions." 5

Thus we have stated that will, which is a mental function, is different from volition, which is an animal function, and the latter originates the spontaneous and instinctive movements of animal life.

The government of will is necessary to a healthful mind, and also, to a healthful and sound state of volition. A defective function of will, under any circumstances, whether caused by injury or disease, induces, more or less, a manifestation of a disordered mind, and is frequently the proximate cause of madness.

Thus all these authorities agree, that the function of volition, is seated in the medulla oblongata, and is manifested by sensation, and the contraction of muscular fibre, producing voluntary motion in man, and among the higher animals; and is governed by the will.

And for the proper co-ordination of the will, with volition, the cerebral masses should be in health; for the function of volition cannot be correct, if the mind and intellect be diseased. But the functions of organic life, respiration, circulation, and digestion, may go on, if the cerebral masses be diseased; or if removed, as proved by the experiments of M. Flourens.

The Understanding, originates in, and is derived from consciousness, perception, reflection, will, and memory; from which also, in a healthful and vigorous state of the mind, result imagination and ideas: and understanding is seated in the hemispheres.

Locke says there are certain qualities or conditions which are required to constitute the understanding, namely, perception, reflection, consciousness, memory, and will, or liberty; the latter he opposes to necessity, and considers necessity passive or physical; and liberty vital, mental, and active; he says we find in ourselves a power to begin, or forbear, continue, or end, several actions of our minds, and motions of our bodies, barely by a thought, or

preference of the mind ordering or commanding the doing