RESPIRATION DURING CELL DIVISION IN THE EGG OF THE SEA URCHIN PSAMMECHINUS MILIARIS

Abstract

The later divisions in the egg of P. miliaris are accompanied by variations in oxygen uptake. As in the embryo more and more cells divide simultaneously, the respiratory variations become more and more pronounced. The phenomenon is interpreted as an extra O2-uptake correlated with the mitosis. During the 4 divisions nos. 5-8, proportionality is approximated between number of cells dividing and extra O2 taken up. Thus, for the divison period considered, the extra O2 consumed by a dividing cell approximates constancy, viz.: it is independent of the size of the dividing blastomere.