In 1873 an inquiry was carried out by the Obstetrical Society of London into the merits of transfusion, the subject having been brought to the Society’s notice by a report of a case by Aveling, and an interesting summary of the evidence was prepared by Madge in 1874. The results do not seem to have been very encouraging, and transfusion was still regarded as a procedure that was only to be used as a last resource. Even at this date the blood of other animals was being used for transfusion, although the practice had been discredited by Panum in 1863 and by others, and a series of cases was reported by Hasse in 1873, in which lamb’s blood was given for various conditions. Other cases were reported from Italy (3) and Russia (101). Sentiment, if not science, seems to have suggested that there was something repulsive in bringing a lamb into the sick chamber and mixing animal with human blood, but it was remarked in a discussion on the subject that “it was only taking lamb in another form.” After 1875, however, there was a decline in the amount of attention given to transfusion which lasted for thirty years. This was probably due in part to the increasing number of fatalities which had followed the more general use of transfusion, but, as Peterson suggests, it was also to be accounted for by the increasing use of normal saline solution for intravenous injection in the treatment of hæmorrhage. There was also a period during which the use of milk was advocated for intravenous therapy (37, 279). Soon after the beginning of the twentieth century transfusion received a fresh impetus which has steadily gained force up to the present time. The free use of cannulæ and syringes had always been hampered by the coagulation of the blood, and it was clearly a great advance to be able to perform a direct transfusion without the intervention of any tube. This was made possible by great improvements in the surgery of the blood-vessels, which were due in the first place to the work of Murphy, published in 1897; they were carried still further by others, such as Carrel and Guthrie, and culminated in the work of Crile, who in 1907 put the technique of direct transfusion on a securer basis than it had ever been before. His method is briefly described in a later chapter of the present work. Meanwhile the chief factor responsible for previous fatalities was being eliminated. The presence of agglutinins and iso-agglutinins in the blood had been detected by Landsteiner and by Shattock in 1901; in 1907 the four blood groups into which human beings can be classified were determined by Jansky and the work was repeated by Moss in 1910.