The variations that may occur in the percentage of hemoglobin in a normal man during the day have been shown to be considerable.1 As much as 26 per cent. has been reported in the course of two hour observations. Numerous factors contribute to this phenomenon.
The question of variations not only in the percentage of hemoglobin but in the color index, red cell volume and plasma cell ratio over two hour periods has been investigated in a series of sixteen cases of anemia. Of these, ten were of the pernicious or addisonian type. The blood was obtained by venipuncture at two hour intervals, beginning at 8 a. m. and terminating at 6 p. m. On each specimen, a red cell enumeration, the hemoglobin percentage by oxygen capacity (Van Slyke) and Dare methods, and plasma cell ratio were determined. From these data, not only the color index and the red cell