Transfusion Of Blood, the operation of introducing into the vascular system of one animal blood taken from the vessels of another. This operation was suggested and described by Libavius early in the 17th century, but it was first successfully practised by Richard Lower in England in 1665. Some years previously it had been ascertained by Robert Boyle that various medicinal substances might be injected directly into the bloodvessels of the living dog, with the result of producing their specific effect upon the animal system, as if they had been introduced by the stomach. Lower's experiments were also performed upon the dog, by connecting, by means of a tube, the carotid artery of one animal with the jugular vein of another, the vein of the second dog being allowed to remain open above the point of connection. Thus the blood lost by the second dog was supplied by that coming from the carotid artery of the first. The consequence was that the animal into whose vessels the blood was introduced in this way by transfusion remained uninjured, while the other died of exhaustion from haemorrhage. These experiments encouraged the idea of performing a similar operation upon the human subject.

This was first done in France in 1666 by Denys and Emmerets. They believed that the operation might result in the cure of chronic diseases by introducing into the veins of the patient healthy blood from a foreign source; and accordingly they transfused the blood of a sheep for this purpose into a man. The first results were said to have been so favorable as to excite the most extravagant anticipations, and to create great enthusiasm in the minds of the medical profession in favor of the operation. But these promises were not fulfilled, and as several instances occurred soon afterward where the operation was followed by bad consequences, there was a corresponding reaction against it, and in 1068 the parliament ot' Paris forbade its repetition except by special consent of the faculty. In 1818 the operation of transfusion was again taken up by Dr. Blun-dell of London, who carefully experimented upon it as applied to its original and legitimate object, namely, the restoration of life after exhausting haemorrhage.

He performed S3 experiments upon dogs, and established by them the following facts: 1, that dogs, when exhausted by haemorrhage, may be resuscitated, even after momentary stoppage of the respiration, by injecting the blood of other dogs; 2, that human blood injected into a dog, in sufficient quantity to supply the loss caused by abundant haemorrhage, produces a temporary reanimation, but does not save life, as the dog dies some hours afterward; 3, that the transfusion of blood, whether arterial or venous, will be successful if the two animals belong to the same species; 4, that the blood used in transfusion need not be conveyed directly from the vascular system of one animal to that of the other, but may be received into a cup and passed through a syringe, without being thereby rendered unfit for the purposes of life. The operation was thus placed upon its proper footing, and one of the important conditions for its success brought into notice; namely, that the blood used for transfusion should belong to an animal of the same or at least a kindred species. This explained in great measure the bad results of the earlier operations, in which the blood of the sheep had been introduced into the veins of the human subject. This fact was still further elaborated by subsequent experimenters.

If the animals used for experiment belong to different classes, as where the blood of a quadruped is introduced into the veins of a bird, or that of a bird into the veins of a quadruped, even in small quantity, it appears to have an actually poisonous effect, and death follows in a very short time. If the animals belong to the same class, but are not of the same genus, as where the blood of the cow or the sheep is introduced into the vessels of the cat or the rabbit, or human blood into those of the dog, there is a temporary reani-mation, but noxious effects afterward follow, and death occurs at the end of some days. These noxious results appear to be due in great measure to the presence of the fibrine of the blood; for if this be removed by beating the fresh blood before its injection, they do not follow, or at least are much less strongly marked. Nevertheless, the blood of animals belonging to a different class, even when de-fibrinated, though no longer actually poisonous, does not resuscitate or preserve the animal experimented on from the effects of haemorrhage. To secure this beneficial effect, the animals must be within certain limits of consanguinity.

If the blood be used fresh, they must belong to the same species; and if it be defibrinated, they must still belong to the same genus. Furthermore, it is found that the red globules of the blood are essential to its vivifying influence. The fibrine may be removed without injury, and in some cases, as above mentioned, even with benefit. But the injection of serum alone, that is, blood deprived of both fibrine and globules, is useless as a means of preserving life. - With these improvements the operation of transfusion has been successfully applied to the human subject. After an abundant haemorrhage there is frequently an interval, often of several hours, during which, although the haemorrhage may have ceased, the patient is evidently sinking, and other means of restoration are of no avail. It is to such cases that the operation of transfusion is adapted. Berard has recorded 14 instances of this kind, most of them cases of haemorrhage after delivery, in which the life of the patient was saved by this means. There are certain rules which it is important to observe : 1. In transfusion in the human subject, it is of course human blood that should be used, supplied by a healthy, vigorous person. 2. But a small quantity, namely, from two to four ounces, should be injected at a time.

This amount is generally sufficient; if not, the in-jection may be repeated after an interval. All that is required by the transfusion is to restore the patient to consciousness and bring him into such a condition that he can take and appropriate nourishment and stimulus. 3. If the injection be made by a syringe, great care should bo taken that the blood be not allowed to fall below its natural temperature of 100° F., and especially that no bubbles of air become entangled with it and thus introduced into the veins. 4. The injection should be made slowlv, and terminated as soon as the requisite effect has been produced. 5. The delay should not be so great as to incur the risk of the blood becoming coagulated, either in the syringe or within the veins of the patient.