LECTURES

MENTAL

ON

DISEASES.

LECTURE I.

Argument.-Mental disease dependent on disease of nervous centres-Its study requires some acquaintance with psychology-Review of the chief mental phenomena, considered by the synthetical method-Simplest phenomena and gradual development of mind- Excito-motory phenomena, and its ternary arrangement of afferent, centrum, and efferent; analogous arrangement with sensational phenomena, or an excito-sensatory system: morbid changes of these are centric or eccentric-Addition of consciousness, out of which the intellect is evolved-Intellectual phenomena of ternary character-Morbid conditions of the intellect, also centric and eccentric-Emotions-Comparison of emotional phenomena with excito-motory acts and will-Volition and voluntary actions subject to similar ternary law-The various emotions and states of emotions as affected in disease-Abnormal volitional acts-Formation of character.

GENTLEMEN,-In order to avoid all misunderstanding, let me state that, in treating of Mental Diseases, I commence with the axiom that the Brain and Nervous System are the organs on which the Phenomena of Mind depend.

I am, therefore, about to call your attention to certain affections of the Nervous system; but, as a celebrated writer remarks, though it is true that mental diseases are brain affections, all brain affections are not cases of mental disease, or insanity. The separation of the particular class of affections which constitute insanity, from the general list of diseases and from other nervous affections, is based on grounds which are somewhat arbitrary-at all events it is not founded upon pure pathology. The laws and the welfare of society render it necessary to distinguish and separate certain individuals exhibiting disturbance of the mental faculties, and to place them under surveillance

and in seclusion; but, as physicians, we cannot accept the requirements of law as a basis of nosological classification; we must study insanity by the light of the general laws of pathology; we must consider it in connection with the general science of medicine, of which it is a part, and by no means an unimportant part, both with regard to its scientific and social bearings. The science of medicine itself becomes defective when it omits the study of this subject.

In our examination of the diseases or states of the mental functions we meet with certain alterations of the normal action to which distinct names have been given. At the bedside in diseases generally we denote all deviations from the normal action of the mind by the general term Delirium. At one time we use the word to signify an act of violence, at another mere incoherent raving, &c. In the study of mental diseases a more precise nomenclature is needed for such various deviations. It will be well, therefore, that we should make a cursory survey of the healthy phenomena of mind; that is, in other words, that we should review the physiology of normal mental phenomena, or psychology, and we shall then be more competent to examine into the abnormal phenomena, and to study their origin, course, progress, as well as their sequence, and connection with each other; in other words, we shall be better able to study the pathology of mind.

I am not about to enter very deeply into metaphysical questions. I agree on the whole with my late friend Dr. Marcé, who in the commencement of his treatise on insanity suggests that metaphysics is more likely to gather light from a study of insanity than insanity is to gain light from metaphysical discussions but I would by no means depreciate the study of mental philosophy, which now forms a part of every wellconsidered scheme of education. I would recommend every student of medicine to make himself acquainted with the physiology of mind, not only by reading works on physiology, but by studying treatises especially devoted to the subject of mental philosophy; and I would particularly mention the writings of Herbert Spencer and Bain, as worthy of perusal.

In this place I shall only attempt to bring before you certain points which have a peculiar bearing upon the subject of insanity.

If we take any simple act of the mind and analyse it, we shall readily distinguish different kinds of phenomena. For example, let us take the act of reading: in this we can trace the following. In the first place, we direct our eyes to the pagein this we recognise what is called the will; next, we see the page-this is a sensation; we are aware of the sensation— that is, we perceive and we are conscious of this perception. We also recognise the letters and words; we compare them with similar impressions experienced at some former period; we remember-we are thus cognizant of the faculty of memory; we also understand and reason about the subject-matter of what we read; we feel the effect of the words-one formula of words will produce the secretion of tears, another will produce the convulsions of laughter. However varied the effect produced, philosophers have reduced the phenomena to three or four heads, included under the four words, senses, intellect, emotion, will.

For the better elucidation of my views I prefer to proceed to the examination of the mental faculties by the synthetical mode. To pursue the subject by this method, we must trace the first indications of sensibility as they are to be observed in the lower forms of animal life. The polyp gives us such an example when it simply opens or closes under the stimulus of light. We have in this simple act the germ or indication of that which in a more highly developed state we call sensibility. The act differs scarcely at all from phenomena observed in the vegetable kingdom: as the closing of the leaves of the sensitive plant, the expansions of the flower under the influence of the sun, &c.

In these low forms of animal life, the organism is homogeneous; there is no special organ of any kind; there is no special organ for sensation, motion, or digestion, but that part digests on which the food falls, that part moves which the excitant touches, that part alone is affected on which the stimulant impinges. In the next stage in development the first approach towards specialty of organs occurs in the addition of points apparently more sensitive to a particular stimulus, as black pigmentary foci, to receive or enhance the impression of light, and with this specialty of action there is attached of necessity an apparatus for transmitting or diffusing the stimulus to other and remoter parts-nerves.

In fact, in ascending the scale, we find established special organs for receiving special stimuli, as eyes for light, muscle for motion, an organ for digestion, nerves for conveying impressions, &c.

But in the polyp, which seizes its prey by its tentacles, we have the principle and germ of an excito-motory system, which is gradually perfected, and becomes, when aided by special sensitive organs, what has been called a sensori-motory system, and which is synonymous with instinct. "Instinct may be defined," says Herbert Spencer, "as compound reflex action, out of which it arises by successive complications" (p. 539).

When the special organs have been increased in number, as when even limbs, or complex motor apparatus, have become developed, and still more when limbs even have been endowed with special functions, as some for seizing prey, others for locomotion, by walking, flying, &c., it then becomes necessary that these multiplied organs should be brought into consentaneous action, and this is done through nervous filaments, and a system of ganglia freely communicating with one another.

The ganglionic communications at first appear to be partial only. We know that segments of insects divided from each other will continue to act independently: thus, the head of a wasp will continue to eat, the thorax and wings will fly, the trunk will move and sting, when the insect is divided into three parts.

The excito-motory or sensori-motory system is developed to such a degree in certain insects, as in the ants or bees, as to approach or even surpass the intellectual acts of the lower kinds of animals. The complex operations performed by the working insect, however, appear to be mostly excited, and probably leave but little impression upon the animal.

The excito-motory system is void of consciousness, of memory, of will, and emotional feeling; but (and this is the particular point to which I wish to direct your attention) the lowest type of nerve function, whether we call it the excito-motory or sensori-motory, consists, as you know, of three acts, viz., (a) the excitant, or afferent act; (b) the centric æsthesis; and (c) the motor, or efferent act: the first acts in a direction toward the centre, second at the centre, and the third toward the periphery. In the lowest animals, these acts are, probably, not performed by

special parts of the organism; but as the organism is elaborated or developed, the three become specialised; and in all the higher animals, the special organ can be particularised.

There is another point, to which I desire also to direct your attention, and with which, from your studies in physiology, you are doubtless familiar, viz., that in the excito-motory system, in which the afferent and efferent nerves are separate, i. e., special, an excitant applied to any part of the efferent nerve produces motion, and that the same effect follows if the central ganglion, say the spinal cord is irritated. In the convulsions of children the excitant is considered to be at the periphery, say at the terminal branch of a portion of the fifth pair; but some convulsive affections are caused by irritation in the central organ, as in certain forms of epilepsy.

Convulsions are said to occur from centric or eccentric causes, according to their origin from central or peripheral irritation. I shall have to refer to this hereafter.

In connection with the system of excito-motor and sensorimotor action, observe, the stimulus is conveyed from the centre to the periphery by nerve-fibres. I repeat, is conveyed-there is a tendency to confound movement with nerve-force; it is the function of muscle to produce motion, and motion is produced apparently independent of nerve-communication, for motion occurs at an earlier period than the era of nerve-formation. In animals in which no nerve exists, motion exists. The organ, call it muscle or contractile tissue, is not even, it would appear, specialised at first.

Movement is therefore clearly due to power inherent in muscle; it is a power resulting from its organism-from the nutritive changes going on within it. And we must also remember that the function of nerve-tissue is nervous energy; it is believed, further, that it is the office of the ganglionic portions to intensify or generate nerve-power, and the nerve-fibres to convey it.

Now, the efferent in the excito-motory phenomena is directed to muscle; the resultant is therefore motion-an act of motility; but in this motor result let me again repeat, there is an action or impression from what has been named the environment of the person, or from the external world by a system of nerves; and since the action takes place at the periphery, there is a