The amounts of blood given in pernicious anæmia have varied. Massive doses have occasionally been given (179), but the general opinion seems to favour smaller amounts, 300-500 cc., the dose being repeated at intervals of two or three weeks. Repeated transfusions have been an outstanding feature of the treatment, and as many as thirty-five transfusions of 500 cc. or more have been given to one patient, extending over a period of thirty months. This is in itself a demonstration of the fact that blood transfusion does not cure the disease; the beneficial effect of each transfusion may wear off in a short time, but by repeating the treatment the patient’s life can be prolonged for months or even years beyond the time when it would otherwise have ended. Although the effect of transfusion is apt to be transient yet it is certain that its good effects are due not merely to the addition of a certain number of healthy corpuscles to the circulation, but, in addition, to an obscurer factor. This can best be expressed by saying that the transfused blood appears to have a stimulating effect upon the blood-forming tissues of the patient, so that more red corpuscles are discharged into the circulation. One observer believes that enumeration of the reticulated red cells may be used as an indication of the hæmopoietic powers of the bone marrow (289). The reticulated appearance is assumed to be characteristic of cells which have recently entered the circulation. The mode in which this stimulus acts is unknown, and the whole subject calls for further investigation. That this does take place is well illustrated by the following details of three cases from Dr. Drysdale’s wards at St. Bartholomew’s Hospital. The transfusions were given by Dr. Joekes, who was also responsible for the estimations of the corpuscles. [Illustration: Fig. 3.--PERNICIOUS ANÆMIA, CASE I] I. A woman, aged 51, had been treated for four years for pernicious anæmia, and when admitted to hospital was becoming steadily worse. The red corpuscles numbered 1,470,000 per cmm., and her hæmoglobin percentage was 32 on October 21, 1918, and by November 19 they had fallen to 750,000 and 25. On November 22 she was transfused with 500 cc. of citrated blood, and a blood count made immediately afterwards showed that she then had 1,410,000 red cells per cmm. On December 12 the number had risen to over 3,000,000, and on January 28 of the following year it was over 4,000,000. This was still maintained in May, 1919, and on the last occasion on which a blood count was made she was found to have 4,400,000, with a hæmoglobin percentage of 90. Since then she has been lost sight of, but would certainly have returned had she relapsed. This case shows what remarkable results sometimes follow a single transfusion and the progressive improvement which follows the initial rise. The diagram shows the results more graphically. [Illustration: Fig. 4.--PERNICIOUS ANÆMIA, CASE II]