An attempt has been made to detect the "embryonic" or "primitive" human hemoglobin that has been reported by other authors. Chromatographic comparisons have detected no significant differences in the hemoglobin components of fetuses in age from 15 weeks to term. The method of alkali denaturation has been applied in conjunction with the chromatographic comparisons, but it also has detected no significant differences in the various samples.
All samples that have been investigated contain a hemoglobin component termed FI. It is present to the extent of about 10 per cent in all samples and presumably is a normal constituent. Its rate of denaturation by alkali is essentially indistinguishable from that of the main component in cord blood and so FI is included in all determinations of hemoglobin F by alkali denaturation.
The results of this investigation lead to the conclusion that there is no "embryonic" human hemoglobin that precedes hemoglobin F in the way the hemoglobin F precedes hemoglobin A in the life of the individual.