We have undertaken a study of the formed elements of the blood of normal infants during the first year, exclusive of the leukocyte and differential count, to secure a base line for comparison with the values in a group of premature infants, studied under identical conditions, to be reported in a later paper.1a A base line of this character appeared to be essential in order to avoid misinterpretation which might result from uncritical acceptance of normal standards developed in localities geographically and environmentally different from New York City. Because the results of the study do not conform completely with data available in the literature, because much confusion has arisen from the use of arbitrary hemoglobin standards and, lastly, because the data of other observers have usually not been subjected to statistical analysis, a separate report of this study has seemed warranted.
I. SURVEY OF LITERATURE
No exhaustive survey of