A putrid state of the blood is frequently spoken of by pathologists, and may be very reasonably expected in the most putrid fevers. MM. Parmentier and De-yeux examined repeatedly that drawn from patients in fevers of the worst form. It did not yield volatile alkali by distillation, nor did it become putrid sooner than blood from the most healthy person. Yet, in various diseases, the albumen seemed affected; its union with the serum was less complete, and its concretion less perfect than in health. By analysis, the buff when present was similar to that from inflammatory diseases, and the coagulum below was tender: it was soluble in water: the solution was coagulated by heat, alcohol, and concentrated acids, while fixed and volatile alkalis rendered the colour more vivid, and prevented the coagulation.

In hectics the red globules have a more brilliant red, and the blood is generally buffy. The latter can be accounted for from increased action, and the former has been lately explained from the more rapid respiration, and consequently from the blood being more frequently-exposed to the oxygen of the atmosphere. It is not, however, considered, that, in the greater number of hectics, the extent of the surface of the lungs is destroyed, in a greater proportion than is compensated by the repetition of,breathing. When we contrast this appearance with the pale colour of chlorotic blood, we think it will be admitted that the cause lies deeper, and has not yet been discovered. If a deficiency or redundance of the iron be allowed to occasion the diminished or increased colour, we must still examine from whence either proceeds.

It was once proposed to relieve diseases of the blood by a bold but singular experiment, viz. the transfusion of the blood of a young healthy animal into the veins of an aged or diseased person, while his blood was at the same time discharged from a distant orifice. The experiment was simple, and consisted of inserting each leg of a syphon into the aperture of an artery of the animal, and the vein of the patient. In the ardour which usually attends a new invention, it was supposed capable of prolonging life .to an indefinite period; of correcting not only diseased states of the fluids, but even of correcting the disposition and temper. By a singular fatality, this project having been often employed, it is said with advantage, certainly without injury, was at once abandoned, in consequence of the death of a person, in which the operation could not be blamed. We can now see how little was to be expected from it, unless we could substitute the life of a calf or a lamb for that of the human body: but, the most zealous follower of Mr. Hunter would not willingly abridge his life to their period by transfusion. Numerous instances of the effects of this practice occur in the early volumes of the Philosophical Transl I 2 L I 2 actions; and the outlines are given with great precision in their abridgment, by Dr: Shaw and his associates.

Another method of relieving diseases supposed to reside in the blood, was by injection of medicinal substances into the vessels; thus the medicine, taking the shorter way, was supposed to be more speedy and certain in its effects. But,' the mildest fluids injected into the circulating system, were soon found to produce very disagreeable symptoms, and the plan is now wholly abandoned.

A singular mode of prolonging life was suggested by Lord Bacon, on the supposition that the heat of the blood exhausted the strength. He proposed cooling it by nitre; and thought that life might be in this way indefinitely prolonged. The experiment was never, we believe, tried: had it been so, little spirit of prophecy is required to foretell the event.

See, on this subject, Haller's Elements Physiologiae, vol. ii.; Plenck's Hydrology; Hewson's Enquiries into the Properties of the Blood, (Philosophical Transactions, vol. lx.) afterwards published separately; Four-croy's Systeme des Connoissances Chimiques; Wells' Observations and Experiments on the Colour of the Blood, Philosophical Transactions for 1797; Memoire de MM. Parmentier and Deyeux, Journal de Physique, vol. xliv.; Cavallo on the Medical Properties of Factitious Airs, 1798.

Blood, discharges of. See Haemorrhages.

Blood, medicines to check the discharges of. See Styptics.

Blood, dragon's. See Sanguis draconis.