hard contracted pulse. These cases are extremely deceiving. On dissection the thoracic viscera often appear healthy, while the ventricles of the brain are perhaps loaded with serum. The correct explanation of the phenomenon appears to be this. The mucous membrane of the bronchia first receives the impetus of the febrile action. After a time the brain suffers, and, weakened by prior ailment, frequently gives way, and the result is serous effusion.

Morbid anatomy.-Dissections in hydrocephalus exhibit the ventricles more or less distended with fluid. The quantity varies much, and can never be anticipated from the violence of the preceding symptoms. From one to six or eight ounces are generally found. The effused fluid does not coagulate on the application of heat, like the serum of the blood, or many other dropsical fluids; nor do we see flakes of lymph floating in it. Where the disease occurs at an early period of life, the quantity of effusion has sometimes been such as to cause a tumour on the anterior fontanelle. In a case recorded by Dr. Baillie, the ossa parietalia were separated to a considerable extent, after being to all appearance firmly closed.* Tumours, probably of a scrophulous kind, have been also met with, of different sizes, situate either in the substance of the brain or cerebellum, or attached to the membranes. It has often occurred, that where hydrocephalic symptoms have been the most strongly marked, no morbid appearances have been discovered in the brain on dissection. In most of these cases the constitution of the child is weak, and yields to the impetus of the disease, before time is given for effusion. In a certain proportion of them, organic disease sufficient to account for death might possibly be found in some other part of the body, were the dissection fully prosecuted.

The appearances presented after death sufficiently prove the inflammatory character of this disease. The effusion of coagulable lymph and of pus are indeed unknown, and in this respect hydrocephalus differs from the phrenitis of adults, but such differences are fully explained by the peculiar circumstances of the infantile constitution.

Causes. The great predisposing cause of hydrocephalus is constitutional debility. We meet with it in the children of

Medical Transactions of the College of Physicians, vol. iv. p. 1.

weakly parents, -in those whose dentition has been slow, and languid,-whose system has been ill nourished, or who have suffered from prior diseases, that leave the body weak and exhausted. We must also connect it in an especial manner with the scrophulous diathesis. Its occurrence in scrophulous families, its alternation with other forms of scrophulous disease, its connection with scrophulous deposits in the brain, and other textures of the body, form the strong grounds on which this opinion is supported. The most common exciting causes of hydrocephalus are teething and cold. In this country it is most frequent in the months of October and November, when the tender frame of the child first feels the influence of the atmospheric cold. To these most frequent causes of the disease, we must add suppressions of tinea capitis, herpetic eruptions, or scrophulous runnings behind the ears; injuries to the head; and previous diseases, especially measles, scarlatina, pneumonia, and hooping-cough. We are authorized in laying it down as a general rule, that in these and all the febrile disorders of children, there is a tendency to that form of phrenitic inflammation which terminates in serous effusion. In the treatment of infantile complaints this principle must be steadily kept in view, as it is practically of much more consequence than any attempt to discriminate such diseases from hydrocephalus by fine and arbitrary distinctions. Lastly, it is unquestionable, that the disease has arisen in many cases without the slightest assignable cause.

Treatment. The object of treatment in hydrocephalus is to diminish that general inflammatory excitement, and that flow of blood to the head, which exist during its early stages; and afterwards to promote, if possible, the absorption of the effused fluid. In what we have called the first or premonitory stage, reliance is to be placed on purgative medicines, particularly rhubarb and calomel, or the powder of scammony and calomel, formerly called the pulvis basilicus. Scammony is peculiarly adapted for the treatment of a disease, in which torpor of the bowels and great depravation of their secretions form so prominent a part.

This dose must be repeated at short intervals, so as to ensure a full action in the bowels. The effect may be aided by injections. A blister to the scalp is often serviceable, especially in habits liable to herpetic eruptions.

When the symptoms of phrenitic inflammation, or, as some would rather say, of cerebral excitement, develop themselves, the jugular vein must be opened, or a vein in the arm, and from four to six ounces of blood taken away. Of the indispensable necessity of blood-letting in hydrocephalus, hardly express myself too strongly. Much of the danger commonly imputed to this disease may be referred to the neglect of this necessary evacuation. If bleeding in the jugular vein, or arm, should unfortunately be found impracticable, or, from the tender age of the patient or other cause, be considered decidedly unadvisable, leeches or cupping may be substituted. Great advantage is always derived from the application of cold lotions to the head. It is hardly ever requisite to apply ice.

When the symptoms indicate that water is effused, bleeding is for the most part ineffectual, and even sometimes absolutely prejudicial. It ought not, however, to be forgotten, that the symptoms of effusion are equivocal, and that an inflammatory condition of the cerebral vessels does not always subside, even when effusion has actually taken place. Blisters should now be applied, either to the crown of the head, or to the arm, or better perhaps to the back of the neck. Considerable caution is requisite in applying blisters to children. Their skins are generally very delicate and irritable, and in feverish states of the body (when the skin is hot and dry) they occasionally produce very high local inflammation, ending in sloughing or gangrene, or such a degree of nervous irritation, as terminates the life of the child by a convulsive fit. The use of active purgatives should be continued; and, with a view of directing the fluids upon the kidney, small doses of the tincture of digitalis may be given every four hours in a simple saline draught. Under the idea of stimulating the absorbents to remove the effused fluid, mercury has been strongly recommended. For this purpose calomel with sugar may be given

Some excellent observations on blood-letting, as applicable to the diseases of infantile life, may be found in Dr. Clarke's Commentaries on the Diseases o Children, chap. vi. pages 148-160.

in doses of two or three grains, frequently repeated. Mercurial inunction may be resorted to where the power of swallowing is lost. In a few cases this mode of treatment has proved effectual. Salivation is not easily excited in children, but it sometimes occurs, and has even occasioned considerable inconvenience.

CHRONIC HYDROCEPHALUS.

The chronic form of hydrocephalus is accompanied by enlargement of the skull; and it is surprising to witness the size which the head will sometimes attain in this disease. On one occasion I found the head of a child, eleven months old, to measure twenty-three inches in circumference. The parietal bones were seven inches apart, and four pints of fluid were contained within the brain. On dissection, the brain appears flattened out, but will be found to weigh about as much as a healthy brain would have done at the same age. In consequence of the yielding of the bones the usual symptoms of compression do not come on. Indeed, in the progress of this disease, the functions of the body generally are very little, often not at all, impaired till a short time before death. It is almost incredible how little the powers of the mind are affected by this disorder. Dr. Monro states, that in no instance seen by him could it be said that the intellect was deranged. In one remarkable case, of twenty-six years' duration, in which the head measured forty-four inches in circumference, the patient displayed a very affectionate disposition towards his parents, entered into the amusements of his brothers and sisters, and enjoyed a tolerably retentive memory.

Chronic hydrocephalus is sometimes congenital; and though it more usually shows itself during the first month, probably commences in all cases while the child is still in utero. The predisposition to it is given by the scrophulous constitution of the parents.

Attempts have been made to afford relief to this apparently hopeless state of disease by tapping, and several successful cases have been recently recorded. The operation, however, is attended with some risk, and is not generally to be recommended. Bandaging of the head has been tried, but without material benefit. The complaint does not necessarily prove fatal at an early age, a few cases being on record of its continuance to an advanced period of life.

CHAP. V.

OPHTHALMIA.

Structures primarily affected. Inflammation of the Conjunctiva. Mild and Purulent. Consequences of Purulent Ophthalmia. Causes. Peculiarities of Scrophulous Ophthalmia; and of Syphilitic Iritis. Principles of the treatment of Common Ophthalmia; of Scrophulous, Syphilitic, and Variolous Ophthalmia.

For many years past surgery has claimed for itself the almost exclusive management of ophthalmic diseases. It will not, therefore, be necessary here to enter into the consideration of the subject further than may suffice to give to the student of physic a general acquaintance with the principal pathological doctrines which it involves. Since the commencement of the present century, when the purulent or Ægyptian ophthalmia first began its ravages in the British armies, the attention of medical writers has been strongly directed towards it; and the variety of large and valuable works on ophthalmia which have recently appeared from the pens of some of our ablest surgeons bespeak at once its importance, difficulty, and extent.

Inflammation may begin in almost every one of the structures of which the eye is composed; but the principal primary seats of ophthalmia are, the tunica conjunctiva, the sclerotica, the iris, and the meibomian glands. The structure primarily implicated depends in a great measure upon the source from which inflammation springs, and certainly in no other disease are the phenomena so remarkably modified by diversities of exciting cause.

Common conjunctival ophthalmia.-The structure most frequently affected is the conjunctiva, in function resembling a mucous membrane, though in appearance more nearly allied to those of the serous class. The inflammation of this membrane is characterized, in mild cases, and where the disease arises from common causes, by pain,-intolerance of light,—a sensation of sand in the eye,-head-ache,-redness of the eye,—and an increased flow of tears. The general febrile symptoms are slight, or perhaps altogether wanting. Under judicious management the disease gradually goes off, without leaving any permanent bad effects.