=Diphtheria.=--In the later stages of some acute diseases due to a bacterial infection, the patient falls into a condition of acute toxæmia, the symptoms of which resemble in some ways those of shock. Harding has drawn attention to this condition in diphtheria; he has produced it experimentally in animals and has treated it by blood transfusion. The toxæmic stage was found to occur on the fourth to the eleventh day. It was characterized by a reduction of the output of the heart with a corresponding fall in blood pressure, an exudation of lymph into the tissues, and an increased specific gravity of the blood. In all these respects it resembled the collapse due to trauma or to hæmorrhage, and it was shown by experiment that the treatment must be directed towards increasing the amount of effective fluid in the circulation and to decreasing its viscosity. It was found that normal saline solution failed to do this; gum-saline solution also failed, and tended to produce a pronounced agglutination of the red blood cells. Blood transfusion, on the other hand, resulted in a considerable number of recoveries. In the aggregate more than twice as many animals survived after transfusion as survived without it, the same amount of toxin being given in each case. These experimental findings are exceedingly suggestive, but the clinical efficacy of the treatment still remains to be proved. Harding found that the amount of blood that should be transfused was one-fifth of the total blood volume; the following amounts are, therefore, recommended for the treatment of children in the toxæmia stage of diphtheria: --------------+-----------+----------- Age. | Weight. | Amount. --------------+-----------+----------- 1½ years. | 21 lbs. | 160 ccm. 2 ” | 28 ” | 200 ” 4 ” | 35 ” | 300 ” 6 ” | 42 ” | 400 ” --------------+-----------+----------- =Pneumonia.=--A condition of toxæmia similar to that seen in diphtheria was also observed in some of the cases of pneumonia which complicated the influenza epidemic of 1918-19. In the United States, among a large number of cases admitted to an emergency hospital, a series of 28 patients, some of whom were moribund, was treated by blood transfusion by Rose and Hund. The results were compared with those in 21 similar cases which were not transfused. The figures seemed to show that transfusion was of some value. Of the 28 who were transfused, 6, or 22·4 per cent., died, and the rest recovered; of the 21 who were not transfused, 9, or 47·7 per cent., died, and 12 recovered. The numbers treated are not large enough to afford statistical evidence that can be relied upon, but the results were at least encouraging.