from drunkenness, hydrocephalus, lateral compression of the chest, ulceration and stricture of the œsophagus, icterus, general dropsy from mitral disease, dilatation of the right side of the heart, senile decay, and hanging. In the human fœtus I have examined the state of the blood in the sixth, seventh, eighth, and ninth months of development; as well as in cases where death has occurred, at or soon after delivery, from extravasation of blood on the brain, from syphilis, from mere premature, birth from atrophy arising from disease of the placenta, and from mechanical injury to the head during labour.

In various inferior animals, including pigs, sheep, oxen, dogs, cats, rabbits, guinea-pigs, and birds, I have observed the blood after death from the following causes: hæmorrhage, intestinal obstruction, poisoning by narcotic gases (viz., chloroform, ether, smoke of puffball, carbonic acid, tobacco smoke, antimonuretted hydrogen, and prussic acid), poisoning by solid opium, by salts of ammonia and potassa, and by antimony; strangulation, both rapid and slow, drowning, electric shock, simple exposure to cold, peritoneal dropsy naturally and artificially produced, shock from blows on the head, extraction of the kidney, inhalation of oxygen, and inhalation of chlorine.

I have also examined the blood in various stages of development, in the fœtal pig, lamb, and dog.

Speaking generally, in regard to these inquiries, I note, in the first place, that the conditions of blood which I have found are as follow:

1. The whole blood firmly coagulated, without any apparent separation of its constituent parts. Or as a simple contracted red clot, lying loose in the cavity,

and from which the serum seemed to have been removed by absorption, either into the structures immediately surrounding, or into the capillaries.

2. The fibrin separated and distinct at different parts; this separation being most commonly seen in the heart, but sometimes in the arteries and veins. The separated fibrin being either (a) in the form of a layer or series of layers upon a red clot; or (b) isolated, and itself filling a cavity, as the right auricle; or (c) modeled into a cylinder, and surrounded or grooved by a red clot; or (d) in the form of a hollow cylinder, more or less perfect, adapted to the vein or artery in which it is situated, and having a cord or column of coagulated red blood running through it; or (e) merely fringing a valve; or (ƒ) laid down on the endocardial surface in the form of a membrane; or (g) lying loose as a cord in one of the large vessels, the remaining blood being either coagulated or fluid.

3. The blood as a loose clot, composed of serum, corpuscles, and fibrin, but all so lightly held together as to be broken up by mere removal; or even so loose, and the contractile properties of the fibrin so reduced, that the whole fluid was brought down to a mere sticky or tarry consistency.

4. Absolute fluidity of the blood in every part, without any discernible trace of separation.

To avoid as much as possible the differences which might occur from the circumstance that the blood in each instance could not be observed at the same period after death, I have taken care, in cases where the coagulation was not well marked, to preserve a portion of the blood, and to watch the processes through which it might pass for at least three days afterwards; this

being the longest period after death at which any of the inspections have been made, except in one or two instances, where the foetus was the subject of inspection.

Referring in detail, but briefly, to the forms of death in which the variations I have thus sketched out have been met with, certain important facts relating to the cause of coagulation stand prominently forward.

I. NORMAL COAGULATION OF BLOOD IN THE BODY.

In instances where life is terminated suddenly, without any long or serious prostration beforehand, or where the respiratory organs have not been primarily implicated in the result, the blood left in the vessels in the normal condition passes, after it is at rest, and if sufficient time be allowed, through the same simple process of coagulation as it does when drawn from the living animal into an open vessel; that is to say, it coagulates first into a simple red clot, afterwards the serum is squeezed out and left free, and ultimately the fibrin and corpuscles remain as a contracted clot. In the body, however, the serum does not always escape rapidly; and, when it does, it must, I think, be taken up by osmosis into the capillary system. This supposition is rendered probable, and may be demonstrated, as I have often found, by the experiment of injecting the vessels of a dead animal with serum or water. The fluid injected disappears in the course of four or five hours; if it is injected into the arteries, it finds its way into the veins, and for a time fills them more or less.

The cases in which I have met with this, the simplest form of coagulation, have been cases of death by syncope, by rapid hæmorrhage, whether internal, as from rupture of the heart or of an aneurism, or external, as

from wounds. The best illustration that can be met with, indeed, of this form of coagulation in the body, occurs in the slaughter-house, after death by the knife. Much, however, depends on the way in which the blood is drawn; for, if a large incision be made, with the head of the animal depending, the loss of blood is sometimes so great, that scarcely any trace of it is met with in the larger vessels, except perhaps here and there a thin cord of red coagulum.

II.

SEPARATION OF FIBRIN WITHIN THE BODY.

In cases in which the blood after death is found to be separated into its constituent parts, i. e. where the fibrin is more or less distinctly divided, either into layers, clots, tubes, or cords, the modes and causes of death are generally very distinctly marked. This condition of the blood occurs, I believe, under three series of conditions: first, in instances where the fibrin is present in the blood in quantities abnormally great; secondly, in instances where amount of fibrin is relatively increased; and thirdly, in cases where some obstruction is thrown in the course of the circulating current, and interferes with or impedes the stream.

Positive Increase of Fibrin. Where the quantity of fibrin is positively increased, the process of its separation appears to be identical with that which occurs out of the body, in the formation of the buffy coat. The cases are also in themselves such as would give the buffy coat, were blood extracted during the patient's life; i. e. they are mostly examples of diseases of the acute inflammatory class, hyperinosis. The causes, also, are possibly identical; viz., increase of fibrin, and an increased attraction of the red corpuscles for each other.

The separation of fibrin in such cases in the circulatory system takes place under two conditions.

1. When the excess of fibrin is slight, the separation may occur after death. The fibrin then lies as a mere layer on the uppermost part of a red clot, thus resembling the buffy coat, except that the cupped appearance is not present, and that the serum, from causes which I have already explained, is abstracted.

2. When, again, there is a great excess of fibrin, the separation may take place gradually during life. In such instances, the fibrinous formations are widely different in their physical conformation from that simple separation described above. These differences arise from obvious causes. In the former example, the fibrinous clot or stratum forms while the blood is in a state of rest; in the latter, it is formed from blood in a state of motion. The differences thus produced are, in truth, so marked, that from the appearance of a fibrinous concretion alone, one may easily tell whether or not it preceded death. If it have been formed from blood at rest, that is, after death, it will be a simple coating on and above a red coagulum; if it have been formed from blood in motion, that is, before death, it will be modeled to the containing vessel or cavity, will be adherent to the walls of the cavity, or will be grooved by the blood currents that have passed along it; while in some examples, where it has been laid down in a vessel, it may be found as a perfect tube enclosing a column of blood, and resembling, in fact, an inner and additional coat of the vessel in which it is deposited.

It would appear, further, that a fibrinous formation occurring during life, takes its root, to use a common phrase, at some point where the current of blood is

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