« ForrigeFortsæt »
• The second treatise, on Hydrophobia, occupies nearly half of the volume, and was left by Dr. Marshal in so perfect a state that it is printed from his MS.with only a few verbal alterations. It gives the history of two cases, and an account of the state of the body after death, with observations on the seat and nature of the disease. The narrative of the cases is very interesting; appearing to be drawn up with great accuracy, and a minute attention to every circumstance which could be regarded as of any importance. The first occurred in a lad of fourteen, the second in a servant-woman of twenty-one years of age; and from the commencement of the attack they were placed under the care of medical men who watched their symptoms with the greatest assiduity. The phænomena which they exhibited forcibly impressed Dr. Marshal's mind with some essential points of resemblance, which he conceived had not been before sufficiently noticed. One of these circumstances was the division of the disease into three stages, which exactly resembled each other in the two cases, except with regard to duration.
" The first state to be noticed was a period of health, an interval of suspence, which was passed between the application of the poison and its effects upon the system.
The second state to be marked was the first stage of the disease, beginning with a local affection accompanied with a general.irritation of the heart and arteries.
The third state, which was the second and last stage of the malady, is a state of madness, beginning when the functions of
the brain become particularly affected, and soon ending in death.' : Dr. M.'s account of the symptoms does not furnish us with any thing that is altogether novel : but some points, which had before been considered as doubtful, are noticed with péculiar care, so as clearly to establish them. Among these, the author insists much on the complete state of mental derangement that occurred in the last stage of the disease; a fact which had been called in question by some respectable writers, who referred the symptoms to convulsion: but, as Dr. M. observes, the violent motions of the body were all voluntary, and were performed under the false impression of some danger to which the patient conceived himself to be exposed, or in order to obtain relief from some pain or uneasiness which he experienced. A very ample account is detailed of the appearances discovered on dissection, and it is remarked that 'throughout the whole internal parts the disease had left palpable and deep marks of its previous existence;' whence Dr. Marshal is led to conclude that the pathology of hydrophobia • is not so incomprehensible as it has been said
to be. He thinks that the poison is absorbed by the wounded part, and, after a certain period, produces an irritation in the ultimate minute arteries' of the part; which irritation is gradually propagated to the trunk, and finally extends to the heart and over the whole circulating system. One of the most remarkable of the morbid appearances was a diminution in the size of the heart and the large vessels, both arteries and veins; which immediately produced another phænomenon that was equally conspicuous, a turgescence and repletion of the small vessels. This morbid contraction extends to all the membranous parts, more especially to the throat, the lungs, the stomach, and the other abdominal viscera; producing in the men:branes an increase of elasticity, and, connected with this last, an increase of the contractility of the muscular fibre. One of the most obvious and characteristic symptoms, although not actually the most important, is the state of the throat, as manifesting itself in the difficulty of deglutition. This circumstance is well explained, on the supposition of there being a morbidly contracted state of the membranous parts concerned in this operation. It consists in a train of mechanical actions, succeeding each other with the nicest adjustment; and it may be easily conceived that any derangement, even in the least of these actions, must destroy the effect of the whole series. After having minutely described the process of deglutition in health, Dr. Marshal contrasts it with the diseased condition :
• When deglutition comes to be performed by such a state of parts as has been noticed in the disease in question, it is expe. rienced to be impracticable, and the attempt is dangerous. Every time the larynx is elevated for swallowing, the glottis is violently contracted, precluding the air too long, while the mouth of the pharynx shuts against the morsel. The person is thrown into instant agitations, just as if seized by the throat; for not only does he experience sudden strangling, but an insurmountable obstacle in the pharynx.
• To proceed. As in a healthy state of the throat, it requires a quicker jerk of the larynx upwards, and a more accurate co-operation of all the parts concerned, when we swallow liquids, than when solid food is swallowed ; so in this disease, it is far more difficult to swallow liquids, than it is to attempt solids. The preclusion of the air lasts longer, and occasions proportionally greater disorder.'
The third part of the volume treats on Mania, and consists of the examination of the brain in a number of instances; principally in order to disprove what was considered as the general opinion when Dr. M. entered on the investigation,
that the complaint left no evidences after death of its previous existence, but that it was altogether mental.” The 13
number dissected was twenty-two, most of the subjects being persons who had been patients in Bethlehem Hospital. In fifteen of these cases, the head only was examined, but in the remainder the dissection was extended to the heart and the other thoracic viscera. These details would have been rendered more interesting, and more useful, if the editor had drawn up the general conclusions which might be fairly deduced from them; since it is this kind of synoptical view that renders the relation of a set of individual cases more particularly valuable. Some of the leading facts are the following:-Ist, In all the cases, water was found, in a greater or less quantity, on the surface of the brain, between its convolutions, in its cavities, or about its basis. 2dly, In seventeen of them the substance of the brain was unusually firm. 2dly, In about one half of the cases, the skull had something peculiar in its form or structure. 4thly, In about one-third of them, the blood-vessels of the brain were in an unnatural state, sometimes much distended with black blood, sometimes small and contracted, and at other times exhibiting a tendency to ossification. Sthly, In two instances, purulent matter is mentioned as having been found within the skull. In many of the cases, it does not appear that any organic affection of the brain was discoverable, which certainly existed before death; so that, although, as far as their evidence extends, the point be established that mania is accompanied by a morbid state of the brain, it still remains to be ascertained whether this be the cause or the effect of the disease.
In the fourth division of this volume, we have observations on the nature of Mania. On this subject, Dr. Marshal left many memoranda, but they were generally in so unconnected and unfinished a state that the editor has been obliged to use his own judgment in the selection and arrangement of them. As a previous step to the knowlege of the pathology of mania, it is necessary to make ourselves acquainted with the functions of the brain and nerves in their healthy state, and with this inquiry he accordingly commences. The primary function of the nervous system is said to consist in its rendering us conscious of our own existence, and of the existence and properties of surrounding bodies. Living systems without brains can have no consciousness; and, in proportion as the brain is injured, so is the faculty of consciousness impaired. The nerves are the media by which the brain receives the impression of external objects: some of them communicating with what are called the organs of sense, while others are diffused more widely over different parts ; * the body, producing the various modes of feeling. The brain
is alike subservient to the intellectual powers, to the internal senses, and to the passions: but all these complicated effects are referred for their origin to the impression of external objects. As the brain is the instrument by which these consequences are produced, it might naturally be supposed that a mechanical injury of its structure would affect its functions; and this, it is alleged, is always found to be the case. Having enlarged on these topics, the author adds; • So much we have advanced respecting the precise function of the brain. It is established, we hope, beyond all doubt, that the brain, so far as a corporeal organ is concerned, gives sensation, intellect, volition, appetite, and passion. These opinions do not materially differ from those that are generally adopted: but Dr. M. next proceeds to a point which has been the subject of much controversy, and on which he embraces the least popular side of the question. Having proved, as he says, that the brain is the corporeal organ of sensation, and of all the powers which naturally grow out of sensation,' he next proposes to shew • that the brain seems to possess no other powers.' He particularly refers to the doctrine that the action and vigour of the muscles denominated involuntary, such as those of the heart, intestines, arteries, and lymphatic vessels, depend on an energy derived from the brain. The principal arguments which he employs to disprove this position are the following. Involuntary contractility exists in living systems that are not furnished with a nervous system; in animals that possess brains, contractility precedes sensibility, as is the case with the chicken in ovo and the fætus in utero, where the heart is formed and acts before the least rudiment of a brain can be detected; and a variety of circumstances in the animal economy tend to shew that the action of the brain is more dependent on that of the heart than the heart on the brain: especially the fact, which seems to be decisively proved by direct experiment, that all the powers of the brain cease immediately with the action of the heart, but that the heart will act after its separation from the brain. - We confess that we have always been disposed to adopt Dr. Marshal's view of the subject, and we think that his reasoning must go far in confirming it. We are not, however, so well satisfied with what he next advances; that the action of the voluntary muscles does not depend on an energy transmitted to them from the brain. He observes that volition only determines the end, and is not directed to particular muscles ; and that the muscles called voluntary, and which appear the most completely under the controul of the will in ordinary circumstances, sometimes act without volition, sometimes without
consciousness, and at other times even contrary to volition. Hence he comes to this conclusion:
For these, and other reasons, we would submit, that the brain is not the efficient cause of muscular motion of any kind : that the energy of muscles is evident; but that it depends neither upon the energy of the brain, nor the vis nervea; for there is no energy in the brain, and no vis nervea of the nerves in the sense these terms have been taken in. The distribution of muscles into voluntary and involuntary gives no illustration of their nature, since no exact limits can be fixed between voluntary and involun. tary muscles -no objection however can be made to using the terms voluntary in respect of muscles, if no more be intended by the term than an energy of muscles accompanying volition.'
After having ascertained the functions of the brain in its healthy state, we are better prepared for entering on the consideration of the change which it experiences in mania. From the view which Dr. Marshal took of the subject, as well as from the result of his dissections, he was led to conclude that, in all cases of derangement of the intellectual powers, there will be an actual disease in the organ from which these powers proceed. He maintained that the original conformation of the brain was more or less perfect in various individuals; and in this way he explained the different effects produced on different brains by the same causes. It is, however, admitted that an examination of the brain after death cannot throw any light on the nature of the disease, excepting so far as to prove that it is connected with the state of the corporeal organ; that which we observe can only be regarded as the consequence : but it is presumed that this, as well as the mental derange. ment, must depend on diseased vascular action. The effused fluid proves that increased action must have existed, but it is probable that a mere increase would not be sufficient without some perversion in the mode of action. This diseased action is produced both by mental and by physical causes, and many circumstances lead us to conclude that these two sets of causes mutually affect each other. Whatever tends to increase the impetus of the blood through the vessels of the brain will produce a state of mental excitement; while, on the contrary, a high degree of mental excitement may augment the action of the vessels : but, before these causes can produce mania, it seems necessary that a predisposition to the disease should exist; and this is supposed to be generally indicated by an obvious malconformation of the skull, either naturally existing or being the effect of injury or disease.
The length to which we have extended this article will prove our opinion of the importance of Dr. Marshal's labours. · Rev. Aug. 1817. D d