other hand, whatever diminishes either the impetus or quantity of the circulating blood, has a correspondent effect on the nervous system; and from the reciprocal connexion and action subsisting between the vascular and nervous systems, the intellectual organs are also affected, but in different ways.

If hæmorrhage is so copious as to produce exhaustion, or if a sufficient quantity of blood be not supplied by means of the nutritive process, not only the powers of the body, but those of the mind, are enfeebled.

Arterial blood has been transfused from an animal into the veins of another, and the recipient animal always exhibits increased vivacity. Dr. Blundell and many others have recently clearly proved, by the transfusing of venous blood from one human subject to another, that life may be sometimes preserved in the most desperate cases of uterine hæmorrhage. The transfusion of blood from animals into the human subject is productive of agreeable feelings, and great flow of spirits; pushed to an extreme, it has occasioned furious madness and death; under other circumstances, it has cured insanity.*

Pressure on the jugular veins of maniacs, by which the blood in the brain accumulates; or on the carotid arteries, by which the brain is prevented from receiving its usual supply of blood, has, Parry says, while the pressure continued, equally produced restoration of the intellectual faculties.

All these facts fully demonstrate how important a part the vascular system performs in the functions of the understanding.

Let us pursue the inquiry, and examine whether the phenomena of disordered circulation establish a stronger connexion with, or throw a clearer light on, those of insanity.

Philos. Trans. vol. ii. p. 617.

COMMENTARY VI.

DISORDERS OF THE CIRCULATION.

HENCE it appears, that there are two morbid conditions of the circulation, which, though directly opposed, immediately influence the intellectual functions, and which, whenever they exist, are manifest and frequent causes of deranged intellect: these are, first, when the blood is in quantity or momentum excessive, and, second, when the blood is in quantity or momentum defective.

1. When the Blood is in Quantity or Momentum excessive.

Plethora and sanguineous determination to the head are often used synonymously in medical language; but they differ widely, inasmuch as determination may exist without plethora, and plethora without determination. Blood may be sent to the brain with a preternatural velocity, and act simply by augmented motion, but be as readily returned by the veins: this is determination. It may be sent either with a natural velocity, or a degree greater or less than is natural; and from some obstructing cause be not returned by the veins in that due proportion in which it has been conveyed to the brainaccumulation, therefore, occurs: this is plethora.

The latter is rarely a primary cause of insanity, but it often induces apoplexy and hemiplegia, and as a sequel, mental derangement: the former, however, very often originates insanity.

Some able pathologists conceive, that in most maladies

increased momentum of the blood is one important and common link in the catenation of causes. Dr. J. Cheyne goes further, and thinks that it would be difficult to point out a disease which has not its commencement in accelerated circulation.*

However this may be, it appears obvious to me that the phenomena which precede the numerous class of maladies affecting the sensorium and mental faculties, are more or less complicated with disorder of the circulating fluids.

The impulse is not always direct to the brain, but sometimes to remote parts, and the brain is implicated by sympathy only; and very often, such determinations are suddenly transferred to that organ.

The facility with which excessive determination of blood to the different organs and parts of the body occurs, and the different local morbid actions thereby induced, we daily witness. But of all parts, the head is certainly the most likely to be overcharged with blood, both from the numerous causes, moral and physical, which accelerate its impetus, and from the mechanical impediments presented to its reflux.

External heat (insolation), violent exercise, certain aliments, alcohol, stimulating medicines, mental emotions, mechanical injuries, all operate on and excite the sanguiferous system. Any of these stimuli are capable of producing all the diseases usually denominated nervous, most of which originate in a disordered state of the circulation, and may precede, be connected with, or are convertible into, actual insanity.

Delicate persons, of a nervous temperament, are most prone to vascular excitation; and so are they to insanity. Neither are those of similar temperament, though of much stronger fibre, exempt from such excitation. Nor

Essay on Hydrocephalus, p. 57.

should it be forgotten, that in all these irritable systems, the maniacal diathesis may be suspected to be latent.

Whether the exciting cause be the result of a moral or a physical impression, still this difference obtains: moral or affective causes produce more sudden and less permanent effects than physical. Sanguiferous determinations supervening on the former, subside sometimes as readily as excited, or with their cause; but when emanating from the latter, they do not cease but by restoring the balance of the circulation. The results of such determinations, however, whether they are temporary or permanent, may be the same. The impetus being given, may occasion delirium, or mania, or apoplexy, or various other cerebral affections, or death.. And when mania is thus elicited, like all other morbid actions once generated, it may long continue, when that. in which it originated is removed, or has ceased.

No symptom is so uniform in all incipient or recent cases, whether of mania or melancholia, as a preternatural heat of the scalp; while, usually, the heat of the surface of the body, or the extremities, is below the ordinary temperature. This symptom originates in partial determination to the head, and nothing is more common in insanity. Mason Cox remarks, that there generally exists a degree of plethora about the heads of maniacs, and frequently when other parts of the system are in a state of exhaustion and debility.*

Delirium is the symbol of insanity, as well as of fever and other acute diseases.

But it has been argued, that mere determination to the head, is not, more than accelerated arterial action, the cause of delirium; because in various states where both are manifest, as in severe exercise, fevers, &c. in which the pulse is excessively quick, and the

* Pract. Obs. on Insanity, p. 30.

face flushed and full, no such phenomenon occurs; and because that the delirium, in many cases of fever and frenzy, begins when the pulse is very little quickened, and often continues when its velocity has subsided. This is very true; but although delirium or insanity may not always be referred to fulness of blood. in the brain, or to increased impetus in the heart's motion, yet it does not thence follow that there is no increased momentum in the circulation of the brain; for, in local inflammations, there is often indubitable: increased local vascular action, without any or little, disturbance of the general circulation. Why, therefore, should not an increased local action be maintained in the brain, as well as in other parts, without a quick pulse, or the ordinary marks of determination to the head? In fact, nothing is more common in mental derangements than to find extraordinary heat of the scalp, throbbing arteries, and suffused eyes, and the pulse quite calm; and dissection repeatedly proves that such increased action in the brain had been going on, when no symptom, while the patient lived, indicated it.

That mania, amounting to fury, and even to death, may be positively produced through the mere medium and motion of the blood, there is decided evidence in the remarkable experiments on the transfusion of blood by Dionis. +

In one instance, where its effect was tried on a man who had been afflicted with periodical mania for seven or eight years, and who had had no sleep for several months, the experiment was attended with complete success. +

+ Cours d'Oper. de Chirurg. p. 498.

This case is so curious and apposite, that I shall not hesitate to transcribe it :-"About ten ounces of blood being taken from the arm, five or six ounces of a calf's blood were transfused into the veins. The