1. Dissolved blood. It occurs in the malignant states of fever. I have seen it several times in the pleurisy, and have once heard of it in a case of gout. I have ascribed this decomposition of the blood to such a violent degree of action in the blood-vessels, as to dispose them to a paralytic state. It is generally considered as a signal to lay aside the lancet. If it occur in the first stage of a fever, it indicates a very opposite practice. By repeated bleedings, the vessels recover their natural action, and the blood becomes reduced to its original texture. Of this I have had frequent experience, since the year 1793. It required three successive bleedings to restore the blood from a dissolved, to a coagulable state, in Mr. Benton. It afterwards became very sizy. If this dissolved blood appear towards the close of a malignant fever, no other benefit than the protraction of life for a day or two, or an easy death, can be expected from repeating the bleeding, even though it be indicated by a tense pulse; for the viscera are generally so much choaked by the continuance of violent action in the blood-vessels, that they are seldom able to discharge the blood which distends them, into the cavity in the vessels, which is created by the abstraction of blood from a vein. There is some variety in the appearance of this state of the blood, which indicates more or less violent pressure upon the blood-vessels. It threatens most danger to life when it resembles molasses in its consistence. The danger is less when the part which is dissolved occupies the bottom of the bowl, and when its surface is covered with a sizy pellicle or coat.
Does not the restoration of the blood from its disorganized state, by means of bleeding, suggest an idea of a similar change being practicable in the solids, when they are disorganized by disease? And are we not led hereby to an animating view of the extent and power of medicine?
2. Blood of a scarlet colour, without any separation into crassamentum or serum, indicates a second degree of morbid action. It occurs likewise in the malignant state of fever. It is called improperly dense blood. It occurs in old people.
3. Blood in which part of the crassamentum is dissolved in the serum, forming a resemblance to what is called the lotura carnium, or the washings of flesh in water.
4. Crassamentum sinking to the bottom of a bowl in yellow serum.
5. Crassamentum floating in serum, which is at first turbid, but which afterwards becomes yellow and transparent, by depositing certain red and fiery particles of the blood in the bottom of the bowl.
6. Sizy blood, or blood covered with a buffy coat. The more the crassamentum appears in the form of a cup, the more inflammatory action is said to be indicated by it. This appearance of the blood occurs in all the common states of inflammatory fever. It occurs too in the mild state of malignant fevers, and in the close of such of them as have been violent. It is not always confined to the common inflammatory state of the pulse, for I have observed it occasionally in most of the different states of the pulse which have been described. The appearance of this buffy coat on the blood in the yellow fever is always favourable. It shows the disease to be tending from an uncommon to a common degree of inflammatory diathesis. It has been remarked, that blood which resembles claret in its colour, while flowing, generally puts on, when it cools, a sizy appearance.
It would seem, from these facts, that the power of coagulation in the blood was lessened in an exact ratio to the increase of action upon the blood-vessels, and that it was increased in proportion to the diminution of that action, to that degree of it which constitutes what I have called common inflammatory action.