There are two classes of facts upon which the above proposition rests. 1st. That either of the phenomena, viz., the convulsions or the structural lesions, may exist without the other; and 2nd. That when the two co-exist, the lesion is often found in parts which experiment has shown to be incapable of producing the phenomena directly. Any other supposition than that of this indirect relationship is inconsistent with the facts of pathology: whereas it is in harmony with what we know of both symptoms and structural diseases. Particular lesions may cause certain phenomena directly; for example, a tumour or softening in certain localities may be the immediate cause of anesthesia or paralysis: but the gross structural change cannot produce directly that which is immediately dependent upon increase of action. The negative symptoms accompanying the positive, and those of the latter which may be over and above the convulsions, are of great service in arriving at a diagnosis; but, when regarding the two classes of symptoms from a pathological point of view, and endeavouring to trace their relations to the organic conditions found post mortem, we cannot too carefully separate the one from the other. There are at least two modes in which lesions or diseases of certain nervous elements may pass over to, and affect others. 1st. Tissues may be involved by contiguity, i. e. a particular element being diseased, as, for example, the vessels with calcareous deposit, or the meninges with excessive fibrinous exudation, adjacent elements-such as the optic commissure or the tubercula quadrigemina-may have their nutrition impaired, not in such manner as to exhibit structural change, but to such a degree as to cause ocular spectra, amaurosis, or convulsions. But 2nd. The lesion or disease of one element may affect another less directly; the elements alluded to may not be contiguous, and their association is effected through a third; for example, hæmorrhage into the crus cerebri of one side causes hemiplegia on the opposite side of the body; and this is its direct or immediate effect. A similar lesion in the hemisphere may so influence the nutrition of parts in the neighbourhood of which it occurs, either by mechanical pressure, by infiltration of the tissues, or other means, that pain, formication, or spasm, may occur in the hemiplegic side; and these are its indirect or remote effects, brought about through contiguity of central organs: but the hæmorrhage may extend into the arachnoid cavity, and instantaneously a paroxysm of general convulsions is observed. Now, this result depends directly upon a nutrition-change of the motor centre; and,inasmuch as the latter is not, in the case supposed, involved in the lesion,-its altered state is an effect of the hæmorrhage, brought about by means of that which lies between the surface of the arachnoid cavity on the one side and the motor centre on the other, viz., the intermediate nerve-tissue. It is by this transference of an irritation from one part of the central nervous system to another, that we must explain the mode in which hydatid cysts or bony spiculæ, for example, between the convolutions on the upper surface of the brain, induce convulsions or other positive disturbances in the func→ tions of those parts which are separated from them by a considerable space. And it is in a like manner that the artificial lesions of the spinal cord which M. Brown-Séquard has shown to be followed by convulsions, produce the latter phenomena.* The order of causation is in such cases precisely the same as that which is observed in eccentric convulsions; the difference being, that in the latter the irritation exists at a greater distance from the motor centre. In many cases, then, the convulsions arising from inflammation set up by a developing tooth, occur in the same manner as those arising from an inflammatory condition of the meninges; and they are not more centric in the latter instance than in the former. If then we use such terms as centric and eccentric in regard of convulsions, we must bear in mind that such terms apply with strict propriety only to the conditions of remote causation ; and that this is the meaning that they have when employed to distinguish convulsions which arise from intracranial disease from others set up by irritation in other parts of the body. The mode in which various lesions in the nervous centres produce similar symptoms, has been gradually explained by our knowledge of reflex actions upon the vaso-motor nerves; * Researches on Epilepsy, p. 68. a knowledge derived from a series of experiments and observations conducted by Bernard,* Brown-Séquard,† Pflüger,‡ Lister,§ and others. These tend to show that the function of one portion of those centres may be exalted or diminished through a reflex action, which determines enlargement or contraction of its vessels, in obedience to an irritation proceeding from some other part. In this way nutrition is affected, and with it there is correlative change in vital activity. The functional relations of the several portions of the nervous centres, and the reasons for thinking that the immediate causes of almost all muscular movements are to be found in the parts at the base of the brain; and that the latter are not only acted upon from below, by eccentric irritation, but also from above by centric conditions, were described by Dr. Carpenter;¶ and thus the intermediation of those organs or ganglia was shown to be the key to explain much of the discrepancy between clinical observations, and much of the difficulty in cerebral pathology. It is by a recognition of the fact, that contractions in the muscles of the limbs, or in the fibres of the blood-vessels, are directly due to impulses derived from the centre of reflex action, and that these may originate from afferent impressions in any part of the body-viz., in the cerebral hemispheres, or in the mucous membrane of the stomach-that we bring into the same category the convulsions from ascarides, and those from tumours in the brain. It is by perceiving that this reflex action may, by augmenting or diminishing the vascular supply in different portions of the brain, give rise to either delirium, pain, and spasm on the one hand, or coma, anæsthesia, and paralysis on the other, that we discover the relation between these symptoms when arising from general systemic disease, or structural alterations of organs remote from the nervous centres, and when occurring in connexion with cerebral or spinal change. * Leçons sur la Physiologie et la Pathologie du Système nerveux. + Researches on Epilepsy. Die sensorischen Functionen des Rückenmarks. § Philosophical Transactions. Part II. for 1858. These views have been elaborated, with great care, while this work has been preparing for the press, by Dr. Brown-Séquard, in his Gulstonian Lectures at the Royal College of Physicians. ¶ Principles of Human Physiology. Edition IV., 1853. And thus, not only is the pathology of the nervous system made much clearer than some years ago it appeared possible that it should ever be, but that of all other organs has received light from this partial solution of the mystery of nervous action. § XII. The classification of convulsive diseases may be effected by regarding the various groups of remote causes. We have then the following :— I. Idiopathic convulsions; including,— Epilepsy proper; "idiopathic epilepsy." Eclampsia puerorum; "idiopathic convulsions" of children. II. Secondary, or eccentric, or sympathetic convulsions ;— III. Diathetic, or cachectic convulsions; from,- Healthy in kind, but morbid in degree; puberty, &c. Retained excreta; urinæmic convulsions, "renal epilepsy." Metamorphosed plasma; pneumonic convulsions, rheumatic, &c. Poison introduced from without; "syphilitic epilepsy," lead, variola, &c. IV. Symptomatic convulsions; from centric disease,— Disease of meninges; tubercle, syphilis, traumatic, &c. In this volume I propose treating only of epilepsy proper, viz., of that form of idiopathic convulsions to which I believe alone the name of epilepsy ought to be applied. RECAPITULATION. I. Disease is the sum-total of modifications in both function and structure. Its name may describe those of the one, or of the other; but it is the combination of them both. II. The measure of disease is, not merely kind or amount of organic lesion, but the degree in which the activities of life, as a whole, are perverted or limited. III. The natural classification of disease is primarily based upon similarity in the mode of perversion or limitation. Thus groups are formed, having practical or clinical resemblance, though differing in regard of the organs structurally affected, and in the nature of their change. Similarity of prominent symptoms is the groundwork of the first division into classes. IV. Symptoms of disease are its appreciable changes in structure or function; they are parts of the disease itself; and from them we have to infer the others, which are inappreciable, but which, with them, constitute the whole disease. V. Some symptoms are physical, chemical, or textural; others are vital, and can only be expressed in peculiar terms-viz., those of vitality. VI. Vital processes are necessarily correlated with physical change; neither ever occurs without the other. Hence so-called functional derangements imply the existence of modifications in the interstitial processes of the organs. Coarse lesions are, then, the remote causes of many symptoms; and that which intervenes between the two is minute, nutritive change, which may or may not affect textural integrity. a. Negative symptoms, or the simple absence of function, may be occasioned directly by solution of continuity in portions of the body. b. Positive symptoms, such as excess or perversion of action, always depend directly upon minute, interstitial change, which may be all that exists, or may be induced by some perceptible lesion. VII. Convulsions, being modified vital actions, depend on modified physical conditions, although these may escape detection. VIII. These conditions are nutrition-changes in the nervous centres. IX. Their nature is the same in all instances where the convulsions are the same. X. Their essence is abnormal increase in the molecular changes of the nervous centres. XI. The remote causes of convulsion are such conditions as |