believed that the blood of different species can be so readily and usefully commingled as that of the same. This hardly needs argument; and the many experiments in this direction have only confirmed natural expectation. But we can not expect to obtain arterial blood from the human subject. We therefore look for some agency by which the venous blood of a donor can be harmlessly transferred to the vessels of the recipient. All the early experiments, however, to attain this result were eminent failures. The blood coagulated in the tubes. During the last few years, the ingenuity of surgeons has been taxed to produce an imitation of the heart, which, taking the venous blood directly or indirectly from the donor, could transfer it rapidly, easily, and gently to the veins of the recipient. Until 1818, the danger from the introduction of air was not recognized. Its fatal introduction into the heart, and its instantaneous destruction of life, the result of accident during operative procedure on the neck, is a matter of surgical notoriety, which has unfortunately been known to occur many times since. This accident can be so readily repeated as an incident to an imperfect mechanical arrangement, that it is one against which every device is designed to specially guard. The danger of coagulated blood, even in minute quantities, would be known to exist in a more or less indefinite way at any time. But the subject of thrombosis and embolism has received its special investigations far more recently than the discovery of the danger from ingress of air; and these are dangers which, in consequence of the light that has been thrown upon them in recent times, would induce the operator to avoid clots of even a microscopic character. I can not, however, believe that life is lost from minute and subdivided quantities of air. This we have on the great authority of Claude Bernard; and direct experiment seems to have settled the correctness of this statement. It is not improbable, also, that minute coagula may be dissolved and disposed of through the emunctories. Still, no prudent surgeon will ever run the risk of either of these accidents. The fear of coagula has induced the resort to defibrinated blood, and, inasmuch as the red corpuscles appear to be the important elements, both for

stimulating nerve-centers in the case of hæmorrhage and for removing the anæmic condition, it has been thought that blood from which the fibrin had been removed was well adapted for these purposes. Is blood that has been defibrinated truly blood, asks Gesellius. To defibrinate blood, it is necessary that while it is coagulating it should be thoroughly whipped with twigs, or, if it be desired to be very nice about the operation, with a glass brush, during a period of several minutes. It must then be strained through a thoroughly clean and closely-woven linen cloth which has been previously moistened. At this time can it be considered as blood? Upon microscopical examination, Gesellius discovers that, even in the defibrinated blood, the corpuscles have arranged themselves in rouleaux. Still, there are many cases of successful and beneficial introduction of defibrinated blood; but it must also be recollected that medicated fluids have been freely introduced into the circulation without fatal results, and saline solutions, indeed, with benefit.

In order to retain the fluidity of blood in its entirety, J. Braxton Hicks, in 1868, proposed to incorporate phosphate of soda, used in a solution of three grains to a pint of water, which was mixed with blood in the proportion of one part of water to three of blood. He made some successes in the lower animals, but he failed in all six of his cases in the human subject.

The profession naturally comes back always to the belief that the blood in its entirety is to be desired. Still, there are many advocates of the method of defibrinization. Perhaps one of the most successful operators by this method is Dr. Thomas G. Morton, who has used it with great success in several cases and has devised a very complete apparatus for preserving the blood free from foreign matters and for maintaining it at a proper and equable temperature. The greater facility of performing the operation of transfusion after defibrinization, as compared with the use of entire blood, has induced its advocates to insist upon its likelihood of producing a better average of results. There is, as they say, no danger from the formation of clots or from the introduction of air. There is no hurry, and hence there is greater accuracy in the operation. Moreover, the quantity of blood

injected can be carefully measured. It may, however, be readily doubted whether minute coagula, still sufficient for capillary infarctions, may not escape through the filter. The formation of rouleaux, which occurs in defibrinated blood, shows that change has already begun, which proves diminished vitality.

Marmonier, in his work upon this subject, has collected thirty-four observations where defibrinated blood has been employed. The results were twenty-two deaths, being a mortality of about two in three. In one hundred and thirteen cases where the whole blood was transfused, there were thirty-four deaths, being a mortality of about one in three. Such statistics must have great weight. Still, it must be confessed that we have no long list of cases applying to special diseases, so that our statistics, being made up of transfusion employed in patients afflicted with every variety of disease, are very unsatisfactory. The arguments raised in favor of defibrinated blood, which have already been mentioned, are supplemented with the asseveration that the removal of the fibrin is of but little consequence, for the reason that the chief function of the blood is to be found in the corpuscles as oxygen-carriers, and the very stirring of the blood in the process of whipping promotes its oxygenation. This certainly is the use of theory beyond warrant. There is no doubt that the mere distention of the bloodvessels with a properly regulated saline solution will produce marvelous results. This has been seen many times in patients in collapse from cholera. This I have witnessed, with amazement at the temporary result. I may, therefore, readily accept the statements of those who have obtained good effects from the use of defibrinated blood.

The point of time at which we must finish the operation when transfusing the entire blood, so as to be entirely secure from danger, either from coagula or the movement in the blood towards coagulation, remains to this day an undetermined question. This is a point difficult to determine, for coagulation takes place in a very short time, and when it has occurred the blood is surely unfit to perform its functions, even if it can be tolerated. We must also recognize the fact that there is a period

of transition from the condition which is perfectly normal to that of coagulated blood. This process is analogous to that of dying. It is difficult, and perhaps impossible, to know when the moribund condition (if I may use such a metaphor) begins. To be entirely safe on this point, we must make the period of transfusion short and definite. We are, however, met with another difficulty in carrying out this indication; for the injection must not be too rapid or too forcible, in order to avoid the production of local congestions, especially in the lungs, and an overwhelming nervous disturbance. To accomplish these various ends, a great deal of ingenuity has been exerted; but it is not my purpose to give a detailed description of these various devices. Suffice it to say that the syringe plays an important rôle in most of them. Now, unless the syringe be held perpendicularly over the recipient, which is not a difficult thing to do, there is constant danger of injecting air. Even with this precaution, unless the syringe be of glass, or have a glass tube in the line of blood-flow, we may commit this dangerous error. The instrument that we have seen so frequently delineated in medical journals as the invention of Dr. Aveling seems to be one of those most secure against this danger. But this instrument may be specially criticised upon the point of danger to the donor by having a needle thrust into his vein and there retained during the time of the operation. Moreover, there are difficulties arising from the length of time required to complete the operation, in the production of coagula upon the sides of the tube, which might become detached in the flow. One of the dangers which results from the introduction of a canula into the veins of the recipient has been happily overcome by Moncoq, in the invention of his mandril, as he calls it, which is retained in the canula until the moment of transfusion. The introduction of a tube rounded at the end, with an opening at the side as in a catheter, has the objection that the blood of the recipient will flow into it and there coagulate during the time of the manipulation antecedent to the transfusion. This has been guarded against, it is true, by filling the tube with water before its introduction into the vein; and this

method has been employed by Professor Nussbaum, and, as he informs me, thus far in his operations without accident. The mandril of Moncoq is simply a solid piece of metal carried through the canula, filling it like the stylet of a trocar, but barely protruding beyond the end, and smoothly rounded. This prevents all coagulation. No form of canula can be considered perfect that is not provided with this addition. I have nowhere seen a statement of the exact time beyond which the operator should regard the continuance of the injection as dangerous. There can be no doubt that the rapidity of coagulation of blood differs in different persons, and also in the same person at different times; but most operators will continue the injection slowly for a period of two or three minutes, for fear of inducing too violent a shock. Human blood will coagulate in this space of time, and, although the first step in this coagulation will begin in the blood that has come in contact with the walls of the instrument, and there, if coagulated, remain adherent, thus allowing the fresh and more vital blood to pass along the center, as in Aveling's instrument, particles of this coagulum may be detached and carried along. It seems to me, therefore, that a rule must be laid down absolutely, that the operation is to be completed by the termination of a specified time. If this time be short, the amount to be injected must be small, in order to avoid the violent impression of a rapid incursion of fresh blood into the veins of the recipient.

At this point permit me to give a description of an apparatus of my own devising, which I believe may be so used as to fulfill all the indications required. It consists of a canula of peculiar construction provided with Moncoq's mandril. This, after being placed in the vein of the recipient, can be allowed to remain a long time without danger of the formation of coagula, because its rounded end prevents the retention of any portion of blood separated from the general circulation. The blood enters through the side of the canula, and, when the moment for its passage has arrived, the mandril is withdrawn. When the moment for the arrest of its passage has come, the mandril can be thrust forward, thus cutting off at once the passage of blood