The Absorption of Oxygen by Plaice Eggs

Abstract

ABSTRACT The rate of oxygen absorption by plaice eggs, contained in a closed volume of sea water, falls when the eggs and water are allowed to remain relatively quiescent. This fall takes place even when a large volume of water is used. It has been shown that small changes in the partial pressure of dissolved oxygen do not appreciably affect the rate of absorption, so that this is not the factor concerned in the fall. The rate of oxygen absorption in a closed volume of sea water does not fall if the eggs be frequently moved. The removal of eggs to a closed volume of fresh sea water at the end of a period prevents the rate of absorption from falling during a second equal period. The removal of eggs to a closed volume of “used” sea water at the end of a period causes the rate of absorption to fall during a second equal period. The addition of urea in small quantities to the sea water has no effect on oxygen absorption. The addition of carbon dioxide to the sea water has a marked effect in lowering the rate of oxygen absorption, and the accumulation of excreted carbon dioxide is probably the factor causing the fall in absorption mentioned under paragraphs 1 and 5. This effect is possibly directly due to the alteration in the hydrogen ion concentration produced by the carbon dioxide. The Respiratory Quotient of young plaice eggs is about ·75.