From the facts which have been enumerated, and from dissections to be mentioned hereafter, it appears, that the disease in its first stage is the effect of causes which produce a less degree of that morbid action in the brain which constitutes phrenitis, and that its second stage is the effect of a less degree of that effusion, which produces serous apoplexy in adults. The former partakes of the nature of the chronic inflammation of Dr. Cullen, and of the asthenic inflammation of Dr. Brown. I have taken the liberty to call it _phrenicula_, from its being a diminutive species or state of phrenitis. It bears the same relation to phrenitis, when it arises from indirect causes, which pneumonicula does to pneumony; and it is produced nearly in the same manner as the pulmonary consumption, by debilitating causes which act primarily on the whole system. The peculiar size and texture of the brain seem to invite the inflammation and effusions which follow debility, to that organ in childhood, just as the peculiar structure and situation of the lungs invite the same morbid phænomena to them, after the body has acquired its growth, in youth and middle life. In the latter stage which has been mentioned, the internal dropsy of the brain partakes of some of the properties of apoplexy. It differs from it in being the effect of a _slow_, instead of a _sudden_ effusion of water or blood, and in being the effect of causes which are of an acute instead of a chronic nature. In persons advanced beyond middle life, who are affected by this disease, it approaches to the nature of the common apoplexy, by a speedy termination in life or death. Dr. Cullen has called it simply by the name of "apoplexia hydrocephalica." I have preferred for its last stage the term of _chronic apoplexy_, for I believe with Dr. Quin, that it has no connection with a hydropic diathesis of the whole system. I am forced to adopt this opinion, from my having rarely seen it accompanied by dropsical effusions in other parts of the body, nor a general dropsy accompanied by an internal dropsy of the brain. No more occurs in this disease than takes place when hydrothorax follows an inflammation of the lungs, or when serous effusions follow an inflammation of the joints. I do not suppose that both inflammation and effusion always attend in this disease; on the contrary, dissections have shown some cases of inflammation, with little or no effusion, and some of effusion without inflammation. Perhaps this variety may have been produced by the different stages of the disease in which death and the inspection of the brain took place. Neither do I suppose, that the two stages which have been mentioned, always succeed each other in the common order of inflammation and effusion. In every case where the full tense, slow and intermitting pulse occurs, I believe there is inflammation; and as this state of the pulse occurs in most cases in the beginning of the disease,