The transfusion of blood, although it may have been practiced earlier than the 17th century, was somewhat extensively studied during a period ranging from 1657 to the close of that century. The principal experimenters during this period were Clark, Lower, Harwood, and King in England, Denys, Em-merez, Prevost, and Dumas in France, and Riva and Manfredi in Italy. The operation consists in taking blood from the vessels of a human being or an animal and immediately injecting it into the circulatory system of another. The operation may be thus described : The subject into whose system the blood is to be transfused, has a slight opening made in a vein (if human the vein selected is generally in the left arm) sufficient to admit the insertion of a small tube. At the same time blood is taken from the veins of another subject, and being drawn into an appropriate syringe, is injected through the first mentioned tube into the veins of the former. Great care is necessary to avoid the inj eetion of air bubbles or small clots. The operation must also be performed slowly, as otherwise a fatal shock may be given to an enfeebled patient. The first experiments of which we have record were made upon dogs, or other domesticated animals of like species, but they were soon extended to transfusion of blood from an animal of one species into the veins of another of widely different species. Thus the blood of sheep was injected into the veins of dogs without apparent injury. Denys and Emmerez were the first to attempt the operation upon a human subject. They publicly injected the blood of a sheep into the veins of an idiot upon two occasions. The first opsration seemed to resultinno injury. In fact it was thought that visible mental improvement was the result. The second, however, resulted fatally, the patient shortly becoming lethargic and dying in that condition. This took place in 1666. In 1667, one Arthur Coyn volunteered to submit to the same opsration, and it was performed upon him twice by Lower and King. The first time ten ounces of sheep's blood were trans-fursed without apparent injury, but on the second trial unfavorable symptoms resulted. The same thing was done in Italy in 1868, but about that time Denys and Emmerez par-formed transfusion upon a ytmng German Baron in Paris, who was afflicted with disease of the intestines, who shortly after died from resulting inflammation. This result occurred upon the second operation, the blood transfused being that of a calf. The French government then proscribed the practice, and Pope also issued an edict of prohibition. Prof. Harwood, of Cambridge University, strove to bring this practice again into notice in 1785, and was followed by Dr. Blundell about the beginning of the present century, who with Prevost and Dumas, first enunciated the true principles upon which its successful application has been made. He showed that the organic differences in the blood of different species, could not but render admixture harmful, and confined the practice so far as human subjects were involved, to the transfusion of human blood solely. Blundell kept a dog alive for three weeks without food by transfusing into its jugular tho blood of other dogs. We recall these facts at this time because the practice seems to be coming more prominently into notice at the present time than it has been for some years past. A German physiologist has latterly been making some experiments in transfusion from which, among others, he derives the following conclusions : 1. That the transfusion of blood taken from fevered animals produces fever. 2. The transfusion of small quantities of healthy blood (up to one-tenth of its entire bulk) produced no considerable increase of temperature. 3d. The transfusion of large quantities of healthy blood (one-fourth to three-fourths of the entire bulk) always caused a fe- ! verish elevation of temperature when a corresponding venesection had preceded the transfusion. The greater the interval between the two operations, the more considerable the elevation of temperature, but this neve* exceeded an increase pf 1 deg.C. . The Medical Record also gives an account of a successful operation for the transfusion of blood recently performed by Dr. Enrico Albanese at the hospital of Palermo, Sicily. A youth aged seventeen, named Giuseppe Ginazzo, of Cinisi, was received at that establishment on the 29th of September last, with an extensive ulceration of the leg, which in the end rendered amputation necessary, the patient being very much emaciated and laboring under fever. The operation reduced him to a worse state than ever, and it became apparent that he was fast sinking, the pulse being imperceptible, the eyes dull, and the body cold. In this emergency Dr. Albanese had recourse to the transfusion of blood as the only remedy that had not yet been tried. Two assistants of the hospital offered to have their veins opened for the purpose, and thus at two ) different intervals, 220 grammes of blood were introduced into the patient's system. 'After the first time he recovered the I faculty of speech, and stated that before he could neither see nor hear, but felt as if he were flying in the air. He is now in a fair state of recovery. The operation has been performed also in cases of collapse from cholera with success, the patient in such cases becoming almost instantaneously warmer and exhibiting most marked relief. The evidences are then, on the whole, favorable to the operation when demanded by extreme cases, as it has no doubt in a number of instances snatched from the very jaws of death those who otherwise could not have recovered.