This consists in an operation for substituting healthy-blood for the abnormal fluid occurring in certain diseases, and for supplying blood in cases in which a deficiency exists by reason of haemorrhage. Ordinarily the blood of a healthy adult is used in transfusion, because ever since the time of Blundell it was supposed the blood of an animal would not functionate properly in the arterial system. This notion is now, however, fully exploded, and Gesellius has especially shown, in his elaborate monograph on transfusion, that lamb's blood will answer the same purpose in the human system as human blood.

As the red globule is the vivifying constituent of the blood, and as the fibrin is non-essential to the most important office, at least of the circulating fluid, it is obvious that defibrinated blood may be used for transfusion. According to the statistics collected by Gesellius, of one hundred and forty-six cases of transfusion with blood without defibrination, seventy-nine, or 54.11 per cent, were successful, and, of one hundred and fifteen cases in which defibrinated blood was used, seventy-nine, or 68.70 per cent, proved fatal. Mr. Higginson, of Liverpool, reports thirteen cases occurring under his own observation, in which mediate transfusion with pure blood was employed, with the result of six successful. The injection of defibrinated blood is free from one source of danger—the introduction of clots into the circulation—which, as Panum has shown, will be followed by the disastrous result of multiple embolisms, or thrombus of the pulmonary artery. Separating the fibrin, however, renders the blood much less capable of performing its office. The necessary agitation in order to coagulate the fibrin injures the blood-globules, and the fibrin itself is necessary to prevent transudations and the recurrence of haemorrhage. With the improved instruments now used for the operation, and with the exercise of the necessary care, there need be no formation of clots, the chief danger in the use of blood containing its fibrin.

Transfusion may be mediate or immediate. Mediate transfusion consists in the reception of the blood in a suitable vessel, and its transference by means of an injecting apparatus into the veins of the patient. Immediate transfusion consists in an apparatus for making direct communication, from the vein of the person or animal furnishing the blood, with the vein of the patient receiving it. A number of appliances have been invented for mediate transfusion. Martin, of Berlin, has, used in his operations a glass syringe provided with a suitable canula for insertion into the vein. Belina invented an apparatus consisting of a receiver for the blood, a hand-ball like that of the spray-douche, and a flexible tube provided with a stop-cock and canula. Beli-4 na, who has treated at great length of the operative procedure, decides that all forms of syringes are objectionable. Higginson proposed and has used successfully an instrument similar to the enema-syringe invented by him. This apparatus can, however, only be used for mediate transfusion. As immediate transfusion is to be preferred, as a rule, it were better to be provided with a suitable instrument for this operation. The instrument invented by Dr. Aveling, and presented to the Obstetrical Society of London in 1864, is at the same time the simplest and most effective. This consists of a hand-ball and flexible tubes like a Davidson syringe, but without valves. There are two canulae attached to either extremity of the flexible tubes—one for insertion into the vein furnishing the blood, and the other for insertion into the vein receiving it. The small-sized Davidson syringe will answer perfectly well by removing the valves, the action of which tends to separate the fibrin, and fitting to the flexible tubes suitable perforated needles or canulae. In using Aveling's instrument it must be first put into water at the temperature of 100° Fahr., and it must be filled with warm water, or better, a warm solution of phosphate and chloride of sodium of a specific gravity of 1020. The object of this is to exclude the air from the apparatus. The next step consists in inserting the canula in a vein—usually of the forearm—of the person or animal furnishing the blood, and in a position so that the blood-current will be in the direction of the current in the patient receiving it. Should the veins of the patient be collapsed, the skin overlying those at the elbow may be transfixed and raised, which will bring into view a vein into which the canula may be inserted—care being used here that the direction of the current shall be toward the heart. The canulae can be held in position by the fingers of assistants. The operator compresses the bulb gently, pressing at the same time the supply-tube between the thumb and finger of the other hand, in order to prevent a reflux of the fluid. When the bulb is emptied, the delivery-tube is pressed between the thumb and finger shifted from the supply-tube, and the bulb is allowed to fill with blood from the source of supply. In this way, successive charges of fresh blood can be delivered without difficulty into the patient's vein. The aspirateur may be used in the same way for immediate transfusion, as has been suggested by Dr. J. W. Howe, of New York, who has used it successfully. He advises the substitution of smaller tubes than those which accompany this instrument, and he has devised suitable canulae for the veins.

The quantity of blood which it is advisable to introduce varies from four to eight ounces. The smaller amount is generally more successful. Too large an amount will seriously embarrass the heart. A further precaution is necessary as to the manner of injection; force is never necessary, and may be very injurious; the blood should be delivered into the vein slowly and gently.

Besides the danger arising from coagulation of the blood and the formation of thrombi, immediate bad symptoms or fatal syncope may come on from the introduction of air into the veins. The utmost care is necessary to exclude air from the apparatus. Phlebitis may also ensue from the injury done to the vein, and the patient's life be put in jeopardy from this cause, but this is a danger much more remote than the introduction of air and clots into the circulation.

As a number of successful cases of transfusion (Gesellius, Hasse, and others) have been reported in which lamb's blood was used, the practitioner is now justified in its employment, notwithstanding Landois has shown by experiment that transfusion of mixed blood does injury to the red blood-globules. If lamb's blood is to be used, the animal should be sufficiently anaesthetized to keep it quiet, and it should be securely tied. A vein may be selected, and immediate transfusion performed with Aveling's instrument or with the aspirateur in the mode already described.

Transfusion is especially indicated in cases in which life is put in imminent jeopardy by haemorrhage. According to Belina, it is in haemorrhage from abortion, and during the first months of pregnancy, that transfusion is most successful. Of thirteen cases of haemorrhage from abortion thus treated, according to this author, eleven had a fortunate issue. Of the cases of post-partum haemorrhage—eighty-five in number—in which this expedient was adopted, fifty-six resulted favorably. Routh, Soden, Hicks, McDonnell, Mudge, Howe, and others, have reported successful cases, not included in the statistics of Belina. In other forms of haemorrhage, haematemesis, intestinal haemorrhage, epistaxis, etc., in which death by exhaustion is imminent, the operation of transfusion is proper. Belina has collected twenty-six cases of traumatic haemorrhage, of which twelve resulted favorably, in two the result was doubtful, and twelve terminated fatally.

Transfusion has also been employed in certain morbid states of the blood, but not with encouraging results. Thus, Belina has collected a number of cases belonging to this category, of which nineteen terminated favorably, in two the result was equivocal, in three temporarily beneficial, and thirty-nine died. Two very interesting cases of the haemorrhagic diathesis successfully treated by transfusion have been reported by Dr. Joseph Buchser, of New York. This form of constitutional cachexia is especially an indication for transfusion. In the treatment of anemia this operation has not been successful. Thus, three cases treated by Stohr, of Wiirzburg, terminated fatally. Cases have also been reported by Concato, Cavaleri, and others. Transfusion has been used very successfully in cases of carbonic-oxide poisoning (Uterhart, Prof. Konig, Prof. Martin), and in phosphorus-poisoning (Prof. Jurgensen).

Eulenburg and Landois advise transfusion in cases of danger to life from poisons for which there are no antidotes. It has been recommended, in such cases, to abstract blood and to supply fresh blood to the suffering organism. Nussbaum has employed transfusion with complete success in epilepsy, and it has also been used with favorable results in eclampsia due to uraemic poisoning.