THE EQUILIBRIUM BETWEEN HEMOGLOBIN AND OXYGEN IN THE BLOOD OF CERTAIN FISHES

¹ THE WOODS HOLE OCEANOGRAPHIC INSTITUTION

1. The oxygen dissociation curves of the blood of certain marine teleosts, the toadfish, the goosefish, and the tautog, have been studied.

2. The oxygen dissociation curves for the toadfish are undulatory in character with two areas concave to the abscissa. The second inflection begins at approximately one half saturation.

3. The oxygen dissociation curves for the goosefish and the tautog change shape with change in pH. At alkaline reactions the curves are sigmoid whereas in acid solutions they are rectangular hyperboæ.

4. The form of the oxygen dissociation curves at constant pH can be described by Hill's equation only under a limited number of circumstances. The curves for the toadfish may be described in terms of equations derived from the assumption that each molecule of hemoglobin combines with four molecules of oxygen.

5. The position of the dissociation curves of all of these fish bloods is markedly affected by pH, and, in addition, with increasing acidity the oxygen capacity is reduced.

6. The manner in which the addition of acid lowers the oxygen capacity may be deduced from the assumption that oxygenation is dependent upon the dissociation of hemoglobin as an acid.