Using the Warburg technic, no change in the rate was observed; this is contrary to the case in Arbacia eggs, and confirms the results of Loeb and Wasteneys. The rates, expressed in terms of cu. mm. O2 consumed per hour per million eggs, are: immature, 168; mature, 170; and fertilized, 167. If expressed in terms of cu. mm. of O2 consumed per unit surface of the eggs, the figures agree with those of the unfertilized Arbacia eggs.