The high hemoglobin content of the blood of the infant at birth as compared with the average value in adults, and its rapid decrease during the early days of life were first recorded by Leichtenstern.1 His observation was amply substantiated by the work of numerous investigators who also showed that the same holds true for the erythrocyte count. The observations of a number of these writers are recorded in table 1. This list is not exhaustive, but includes the more frequently quoted figures of earlier authors and those of the more recent ones whose work covers the period from birth to the tenth day of life.
There is a wide variation in the figures quoted, and their absolute accuracy is doubtful if judged by a present day standard of values. The relative accuracy within each series, however, is probably high, and the uniformity with which they show a considerable