Apoplexy appears in the body under all these circumstances, both in the form of the cavity, and, not unfrequently, in the capillary form.

Hemorrhage very commonly occurs in the brain in persons laboring under simple hypertrophy, or hypertrophy with moderate dilatation of the left ventricle of the heart. The coincidence of apoplexy with this disease of the heart is so constant as to afford ground for stating it as a rule (constitutio apoplectica cordis).

The arteries are very often found diseased in cases of apoplexy, in the form of bony or atheromatous concretions, and of fatty degeneration and brittleness of their middle coat. The arterial trunks, especially within the cranium, are then also thickened, rigid, ossified, and brittle, as well as enlarged (especially in the form of aneurisma cyrsoideum). Hence it may be inferred, that the more minute arteries, and even the capillaries within the brain, are in a similar condition: especially as the former are, in fact, sometimes found ossified, and the brain appears as if filled with stiff wires. This, of course, very often coexists with hypertrophy of the heart.

The brain is very liable to hemorrhage, if it be the seat of atrophy, whether spontaneous or however produced; but especially of that atrophy which is the result of previous apoplexy.

Finally, it is very common in advanced life, when the two last-mentioned causes are so often present together. All these forms of apoplexy appear in the body as more or less extensive cavities, and they are very often rapidly fatal.

Reflecting on these circumstances under which hemorrhage occurs in the brain, we discover the proximate causes to be, in general, congestions, excessive action of the heart, and disease of the bloodvessels. All, when they have attained a certain degree, lead to rupture of the vessels.

The congestions are of various kinds: convulsions produce congestion, which may be active or passive, according to circumstances, and rupture the vessels by the violence of the heart's action.

Apoplexy in the vicinity of tumors, or of inflamed and obstructed veins of the pia mater, or sinuses of the dura mater, or when occurring in connection with morbid density of the lungs, and consequent dilatation of the right ventricle of the heart, is the result of mechanical hyperemia, whether the cause of the hyperemia be near the apoplectic spot or remote from it.

Apoplexies which occur during, or subsequent to, typhus and typhoid fevers, arise from the congestions (active and passive) which are notoriously so frequent in the brain, as well as in other organs, in the course of those diseases.

A similar remark applies to the apoplexy met with in the course of Bright's disease of the kidney; in the production of which, however, mechanical influences must also be taken into account, especially the defects which are so frequent in the valvular apparatus of the endocardium.

In the apoplexy of congenital hydrocephalus, the congestions which give rise to the rapid increase of the original affection, and the stretching of the cerebral vessels which results from this increase, both predispose, the latter mechanically, to rupture the vessels.

But the hitherto unnoticed congestions, arising from vacuum in atrophy of the brain, are of by far the most importance. These, when alone, and more especially when combined with brittleness of the vessels, are, without doubt, the cause of the frequency of apoplexy in advanced life, and particularly of its recurrence in some cases.

The hypertrophies of the left ventricle of the heart, mentioned above, occasion rupture of the cerebral vessels, by the violent impulse which they give to the blood.

The disease of the vessels alluded to, involves, as is well known, brittleness, and a tendency to easy rupture of their coats. Such a state of the coats of the vessels appears to some extent necessary as a cause of apoplexy, for it is often observed that the deepest congestions, whatever their nature, but especially those intense mechanical ones which give rise to cyanosis, do not produce apoplexy.

And, further, the last two causes, viz., increased impulse of the left ventricle, and disease of the vessels, have such a reciprocal supplementary influence, that the more developed one is, the less amount of the other seems necessary to occasion apoplexy. Thus, so soon as the disease of the vessels has reached a certain extent, hemorrhages very commonly occur in the brain, without increase of the action of the heart, and during a state of quietude both of body and mind. A similar occurrence has been already referred to, in the instance of spontaneous rupture of large arteries. (See Dissecting Aneurism, vol. iv).

There is no single cause that will account for the frequent repetition of attacks of apoplexy in many individuals, and its simultaneous appearance at several different spots in the brain, but the presence of disease of the vessels. This also partially explains its happening symmetrically in corresponding portions of the brain at the same, or nearly the same, period. (See the remarks on the symmetrical occurrence of Disease of the Arteries, vol. iv).

The liability to cerebral hemorrhage is of course greater, in proportion to the number of the adduced causes that are present. The congestion arising after atrophy of the brain from vacuum, within the cranium, hypertrophy of the heart, and disease of the vessels, very frequently exist together in advanced life.

Among the predisposing causes, all mention of the so-called habitus apopleeticus might be omitted. And the omission would be justified by the facts; for the notorious "Constitutio Apoplectica" is a mere hypothesis, which is refuted on every occasion. The apoplectic habit predisposes much more to congestion and vascular apoplexy of the lungs, which, indeed, as it induces acute oedema of those organs, is very commonly fatal, and is, unquestionably, the most frequent of all the modes of sudden death.

I have also made no allusion to yellow softening of the brain, as a predisposing cause of apoplexy. But, without entering into any further observations, I may remark that, though it not unfrequently follows, I do not recollect any case in which yellow softening of the brain, as a primary disease, had given rise to hemorrhage.

It appears from what has been said, that as the occurrence of hemorrhage in the brain is entirely mechanical, all the predisposing causes are mechanical also.

Though quite convinced that this is the fact, I can scarcely avoid entering upon the question as to the existence of some morbid state of constitution, or dyscrasia, as a cause of apoplexy; especially as analyses of the blood of apoplectic persons have recently been published, the results of which seem to point to the blood as the cardinal predisposing cause of apoplexy.

It may be reasonably doubted whether any morbid state of the blood could have the effect of rupturing vessels without some previous alteration in the structure of their coats: such a result could ensue only from a state of morbid expansion of the blood; such for instance, as occurs in typhus and typhoid fevers, in combination with congestion. I certainly, however, agree so far, that a certain anomalous condition of the blood does coexist with those circumstances under which apoplexy is most frequently observed; only, as we shall see, it never is an essential predisposing cause, but is itself conditional upon and subordinate to the mechanical relations. Such are:

1. The abnormal state of the blood which is developed in the course, or as the consequence, of hypertrophies of the heart - a venous crasis - cyanosis.

2. That morbid condition of the blood, which gives rise to the accumulation of an inner membrane upon the vessel by deposition from the arterial blood, and thereby to the so-called ossification of the arteries: and also that morbid condition which, after deposition has taken place within the arteries, may be occasioned by the absorption of the elements constituting the atheroma of the artery, especially the fat. No accurate information has hitherto been obtained as to the characters of these morbid states of the blood.

3. A change in the condition of the blood, which occurs in advanced life, and is brought on by atrophy of the brain, but which loses its importance in the presence of the coincident mechanical causes.

The results of the analyses instituted by Andral and Gavarret, on the blood taken from persons suffering from the preliminary symptoms of apoplexy, as well as after the attack, prove clearly the existence of a morbid condition of the blood, but I maintain that they lead to no further result than that the blood of the persons spoken of, is thus composed. So long as more numerous and more widely extended analyses are wanting, it may be asked, without reference to the denial that this state of the blood gives a predisposition to hemorrhage in the brain:

1. Is not this just the condition of the blood which is found in individuals with hypertrophy of the heart, or in those who have ossification and atheroma of the arteries, or in aged persons, and individuals with atrophy of the brain?

2. Has not the disease of the brain itself (apoplexy), either while impending, or after its occurrence, already produced a change in the state of the blood in those very persons whose blood was examined? This question may the more fairly be asked, considering on the one side, the important influence exercised by the brain on the formation, or vegetation, of the general mass of the blood; and, on the other, the deficiency of analyses of the blood in diiferent diseases of the brain, with which the blood in apoplexy might be compared.