Summary. Tbe production of baemoRlobin C (Hb-C) wa.s examined in tbree sheep and two goats wbicb were kept anaemic by bleeding for 5-7 weeks. A fourtb sbeep was made acutely anaemic Ijy bleeding severely for tbree days.In the chronically bled sheep the production of Hb-C wa.s variable and difficult to maintain unless the animals were made severely anaemic.In tbe goats tbe replacement of the ^ chain was almost complete witb an anaemia wbicb was equivalent to tbat produced in tbe sbeep. and Hb-C could be maintained for a considerable period.In the acutely bled sbeep Hb-C increased to a maximum by tbe 16th day, ReticulocytosLS was not marked, but, in general, an increase occurred about 15 days before maximum Hb-C production was evident.Erytbropoietin activity was examined in four animals witb variable results, bnt in the severely bled animal it was evident before tbe reticulocytes appeared. Tbis activity did not appear to he related to tbe amount of Hb-C whicii was produced.The elimination of Hb-C from tbe (irculation was very variable, but tbe rates of decrease in goats were slower than in sbeep.INTRODUCTION.

A new hemoglobin was produced in sheep with Hb A during experimental anemias. This hemoglobin, called Hb Aα, had different electrophoretic characteristics and denatured with alkali at a faster rate than normal Hb A. It also showed electrophoretic differences to Hb B and Hb F. Hb Aα was located almost entirely in the reticulocytes produced during the anemia. The reticulocytes produced in anemic sheep with Hb B contained a hemoglobin which showed only minor differences from the normal hemoglobin on electrophoresis. However, it denatured at a faster rate than the normal hemoglobin. It is postulated that Hb Aα is a relatively unfinished hemoglobin associated with the immature erythrocytes produced after a severe anemic stress. It did not appear to be fetal hemoglobin.