ON THE RATE OF OXYGEN CONSUMPTION BY FERTILIZED AND UNFERTILIZED EGGS : I. FUCUS VESICULOSUS.

1. The unfertilized eggs of Fucus vesiculosus, in the dark, consume about 5.2 mm.(3) O(2) per hour per 10 mm.(3) eggs. 2. With an illumination of 100,000 foot candles in photosynthesis they liberate more than twice as much oxygen as they consume. 3. The actively swimming antherozoids or sperm of Fucus consume oxygen at a very high rate: 25.5 mm.(3) O(2) per hour per 10 mm.(3) antherozoids. 4. Immediately following fertilization, in the dark, the Fucus eggs increase the rate of oxygen consumption to about 190 per cent of the prefertilization rate. 5. This rate for fertilized eggs, about 190 per cent, is maintained uniformly for 13 or 14 hours, after which there is a barely perceptible rise until 24 hours (when measurements ceased). At 18 degrees C. 50 per cent of the spores in a population have completed the first cell division about 15 hours after fertilization.