unless the membranes are taking on the inflammatory action. The general history and progress of the disease, the comparatively soft and yielding pulse, the real prostration of the vital energies, and the peculiar expression which seldom fails to attend continued fever, all serve to assist our diagnosis; while the peculiar symptoms which happen to mark the prevailing fever of the period, the irritable bowels at one time, the exanthematous eruptions at another, furnish, in many cases, still further diagnostic marks.

In acute mania the evidence of mental disturbance greatly outweighs that of bodily disease, which is often but trifling, except as regards the derangement, of a greater or less continuance, of the digestive organs; and throughout the attack the tendency to take on the form of paroxysms of excitement, alternating with periods of comparative tranquillity, is much more marked; while the pulse, though it corresponds in some degree to these changes, seldom deviates so much from the natural standard, either in regard to quickness, to inequality, or to hardness, as it does in Arachnitis.

In Delirium tremens, the softness of the pulse, often approaching to feebleness-the open and perspirable state of the skin-the peculiar character of the delirium, in which even acts of violence appear the result of apprehension and suspicion rather than of any other mental condition—will be circumstances on which our diagnosis may be founded.

The exciting causes of Arachnitis are, mental excitement and anxiety-exposure to the vicissitudes of temperaturethe intemperate use of spirituous liquors-external injuries, and diseases taking place in the bony structure of the head; besides which, it not unfrequently arises in connexion with other affections of the system, as fevers, delirium tremens, rheumatism, and the exanthematous diseases.

Prognosis.-The prognosis in this disease, unless seen and

detected in its first stages, is very unfavourable; whereas if early recognised and treated with energy, the disease is generally removed, but is apt to leave some weakness of mind or susceptibility of body, requiring much care for many months. The more favourable indications are a cessation of the local with a proportional diminution of the general symptoms. The circumstance which portends a bad result, is the advance of the disease, in spite of remedies, to that condition which has been pointed out as marking the second and third stages of Arachnitis; whilst the more the symptoms bespeak great prostration, or lead us, by the indications of lethargy, coma, and convulsions, or involuntary discharge of urine or fæces, to a belief that effusion is taking place, the less can we encourage hope.

Treatment. Where an organ so important to life as the brain or its appendages is involved in inflammation, the most active means should be adopted; and the moment that we have satisfactorily ascertained the existence of the disease, or even arrived at a tolerable certainty that the symptoms bespeak its approach, we must have recourse to free bleeding from the arm, so as to affect the general system as indicated by the pulse; and to active purging, for which purpose, five grains of calomel, and ten of colocynth, may be given, followed by the senna draught, repeated till the bowels are ef fectually cleared; or if, from the difficulty which the diagnosis often presents, we have considerable doubt how far the symptoms may be referable to the commencement of fever or of delirium tremens, we may at first try the effect of the purgative alone, and watch the symptoms for a few hours before we have recourse to the free abstraction of blood. Time, however, must not be lost: the bleeding must be performed, and repeated after a short interval, and must be again repeated according to circumstances; and calomel

and antimony must be administered in frequent doses-two grains of calomel, with a quarter or sixth of a grain of the antimonii potassio tartras being given every third or fourth hour; and should this be found to run off by the bowels, the hydrarg.ecretâ., in four-grain doses, with chalk mixture or a few grains of the pulvis ipecacuanha compositus, may be substituted; or a small quantity of opium may be added: though, upon the whole, it is better, in every instance, to avoid opium as much as possible where the brain is the seat of vascular disease.

The head should be shaved, and kept cool with ice or evaporating lotions, whilst all noises, and every external source of excitement, should be carefully avoided. As the symptoms recede or moderate in their violence, cupping from the nape of the neck, and leeches to the temples, will serve to keep down the inflammation; their repetition being determined by the general evidence of remaining power.

When as much has been done as prudence will allow, or as the symptoms authorize, by these more direct methods of depletion, if the symptoms still continue, mercurial remedies must be persisted in till the constitution is brought completely under their influence; and with this view a drachm of the mercurial ointment may be rubbed on the insides of the arms and thighs two or three times a day, and such forms of mercury given internally as will not disturb the bowels.

In this stage of the disease, blisters will be very useful, and may be applied between the shoulders, to the nape of the neck, behind the ears, or even to the scalp itself; and if there have been difficulty in affecting the system with mercury, the blistered surfaces may be dressed with the mercurial ointment.

At this more advanced stage of the disease, great care

should be taken to prevent the remaining strength of the patient from being exhausted, which must be done by mild nutriment and a cautious regulation of the bowels; for should diarrhoea come on, he will rapidly sink. It may be necessary, even while the mercurial treatment is adopted, whether with a view of subduing low inflammatory action, or of favouring absorption, to have recourse to a certain quantity of stimulus, more particularly to ammonia in its different forms. The sesqui-carbonate of ammonia in excess, in a state of effervescence, with citric acid or lemon juice, will be grateful to the stomach, if sickness or nausea be experienced, or the ammonia may be given in the infusion of serpentary.

When the symptoms have gradually subsided, the most careful management will long be necessary to regulate the diet and avoid every excitement; for not only have we to fear relapse, but to dread lest some marked change should have taken place in the brain which may lead to a permanent diminution of the mental energy.

INSIDIOUS ARACHNITIS.

Besides the acute arachnitis which has just been described, there is a more slow and insidious form of the disease, which gradually creeps on, and is apt to make considerable advance before its real character is at all suspected. It begins by uneasy sensations over the whole body, pains in the limbs, slight headache and chills, loss of appetite and nausea, or even vomiting; and then for many days a sense of general illness only, with some degree of cerebral oppression, unattended by severe symptoms, but rendering the patient unfit for his ordinary avocations. This condition may continue for two or three weeks, varying from day to day, till the more decided symptoms of cerebral mischief, intense headache, frequent vomiting, and perverted sensa

tions, are gradually developed, and a protracted state of disease terminates, in slow effusion into the meshes of the pia mater or into the ventricles of the brain, indicated by a state of coma and subsultus,—or in the effusion of a more decidedly albuminous nature, spread over the arachnoid lining the dura mater, or the serous surface of that situated over the hemispheres. The mind of the practitioner should always be on the alert to watch and appreciate symptoms of this insidious kind; and they must be met by some general depletion in the commencement, by local depletion, by counter-irritation, and above all by the action of mercury.

The membranes of the brain are subject to a still more slow effusion of serum, depending generally on derangement of the circulation, and gradual changes either in the heart and large vessels, or in the more distant organs; but this effusion cannot be considered the result of inflammatory action, nor is it frequently accompanied by that state, and will be more properly considered amongst the causes producing pressure and paralysis.

CEREBRITIS.

CEREBRITIS is the term used to express the inflammation of the substance of the brain. The symptoms by which it is marked are usually much more obscure than those which attend inflammation of the membranes. It is seldom met with in its acute form, except as an extension of Arachnitis, or as the result of injuries and previous changes or deposits in the brain; occasionally, however, no such antecedent disease can be traced. It presents many of the symptoms observable in Arachnitis, but is almost always less violent in its attack: it is often accompanied by little or no acute pain, but rather by a dull headache; occasionally, however, the pain is severe, especially if the inflammation involves the membranes. Cerebritis is more apt, likewise,