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. Here, as upon a former occasion, we may say with concern, if bleeding be indicated by all the appearances of the blood which have been enumerated, how many lives have been lost by physicians limiting the use of the lancet to those cases only, where the blood discovered an inflammatory crust! These remarks upon the relative signs of inflammatory action in the blood-vessels, should be admitted with a recollection that they are all liable to be varied by a moderate, or violent exacerbation of fever, by the size of the stream of blood, and by the heat, coldness, and form of the cup into which the blood flows. Even blood drawn, under exactly equal circumstances, from both arms, exhibited, in a case of pleurisy communicated to me by Dr. Mitchell, of Kentucky, very different appearances. That which was taken from one arm was sizy, while that which was taken from the other was of a scarlet colour. That which is drawn from a vein in the arm, puts on, likewise, appearances very different from that which is discharged from the bowels, in a dysentery. These facts were alluded to in the Outlines of the Theory of Fever[56], in order to prove that unequal excitement takes place, not only in the different systems of the body, but in the same system, particularly in the blood-vessels. They likewise show us the necessity of attending to the state of the _pulse_ in both arms, as well as in other parts of the body, in prescribing blood-letting. When time, and more attention to that index of the state of the system in fevers, shall have brought to light all the knowledge that the pulse is capable of imparting, the appearances of the blood, in fevers, will be regarded as little as the appearances of the urine. [56] Vol. iii.