Changes in the blood and the bone marrow picture of the Pharaoh quail (Coturnix coturnix Pharaoh) chicks as a manifestation of adaptation to postembryonal life.

1. The aim was determination of the rate of adaptation of the respiratory and defence functions of the blood and bone marrow of quail chicks. 2. In the early post-hatching period, enhanced haemoglobin synthesis is the mechanism adapting the bird to the rich oxygen conditions beyond the egg. 3. In 2-week-old chicks, the increased respiratory function of the blood is associated with a parallel rise of the erythrocyte count and haemoglobin content. 4. The defence mechanisms of the chick in the first days after hatching are mainly connected with a high content of heterophilic granulocytes and in older chicks with a rising lymphocyte count.