Methods used in preparing Arbacia eggs for respiration studies, in carrying through the manometric determinations, and in estimating egg quantities have been reexamined.
Discrepancies in previous results are almost entirely due to a steady error in measuring egg volume by centrifuging. Volumes so obtained averaged 80 per cent too high.
The respiration of unfertilized eggs of Arbacia punctulata at 21°C. is 0.9 c.mm. O2 per hour per 10 c.mm. of eggs.