Chapter XIV.

1. The following is the nature of the blood. This is most essential and common to all sanguineous animals, and is not superadded, but exists in all animals that are not in a perishing condition. All the blood is in a vessel called the veins, but in no other part of the body, except the heart. The blood of all animals has no sense of touch, nor has the excrementitious matter in the stomach; neither have the brain, nor the marrow, any sensation of touch; but wherever the flesh is divided, the blood flows in the living subject, unless the flesh is perishing. It is the nature of the blood to have a sweet juice, as long as it is healthy and a red colour, and that is bad which either by nature or disease is black. The best kind of blood is neither very thick nor thin, unless it is vitiated either by nature or disease.

2. In living animals it is always warm and moist, but when taken out of the animal the blood of all creatures coagulates, except that of the stag and deer, and perhaps some others of the same nature. The blood of all other creatures coagulates, unless the fibre is taken out of it. Bullock's blood coagulates faster than that of any other animals. Amongst sanguineous animals, those which are both internally and externally viviparous, have the most blood, and after them the oviparous sanguineous animals; those which are well disposed, either by nature or by health, have not a great deal of blood, as in those that have just drank; nor a very little, as in those which are very fat. Fat animals have pure blood, though the quantity is small; as they become more fat they lose a portion of their blood, for fat is free from blood. Fat is not corruptible, but blood and the parts that contain blood are very corruptible; of these the parts surrounding the bones are most corruptible.

3. Man has the thinnest and purest blood, that of the ox and ass is the thickest and blackest of all viviparous animals. The blood is thicker and blacker in the lower than in the upper part of animals. The blood palpitates in the veins alike in all animals; this alone of all the fluids exists in every part of the body of living subjects, and as long only as they are alive. The blood first of all exists in the heart of all animals before it is distributed through the body. When deprived of their blood, or if the greater part escapes, they faint away; but when a very great deal is lost, they die. When the blood becomes very much liquefied, illness ensues, for it becomes like serum, and flows through in such a manner, that some have perspired blood; and when taken out of the body, it does not coagulate into a mass, but into separate and divided portions.

4. In sleeping animals, the blood in the extremities is diminished, so that it does not flow freely when they are pricked. Blood is formed from serum, and fat from blood. When the blood becomes diseased, hæmorrhoids are produced, either in the nose or anus, and a disease called ixia.[96] When the blood becomes corrupted in the body, pus is formed, and from pus a scab. The blood in females differs from that of males, for it is more thick and black in females of similar health and age. In the whole of the body the quantity of blood is less in females, but internally they are more full of blood. Of all females, women have the most blood, and the catamenia are more abundant in them than in other females.

5. When this blood is diseased, it is called a flooding. Women have a less share in other diseases; but a few are afflicted with ixia, and with hæmorrhoids and bleeding from the nose; when any of these take place, the catamenia decrease. The blood differs in proportion to the age in quantity and appearance, for when very young, it is more like serum, and very abundant; in the aged it is thick, black, and in less quantity; in those in the prime of life it is between these. In aged persons the blood coagulates quickly in the body, or on the surface; but in young persons this does not take place. Serum is imperfect blood, because it has not ripened, or because it has become more fluid.