THE EFFECT OF LACK OF OXYGEN ON THE SPERM AND UNFERTILIZED EGGS OF ARBACIA PUNCTULATA, AND ON FERTILIZATION

¹ From the Washington Square College, New York University and the Marine Biological Laboratory, Woods Hole

1. Unfertilized eggs of Arbacia are not visibly affected by complete lack of oxygen for a period of 8 hours. After an exposure of 3 hours they recover immediately on admission of air; after a longer exposure, when air is readmitted and the eggs are fertilized, there is a slight lag in the formation of the fertilization membrane and in time of cleavage.

2. Sperm of Arbacia are rendered motionless by lack of oxygen, but are otherwise unaffected for 2 hours. They recover immediately on admission of air. After 3 hours some of the sperm are irreversibly injured, and after 4 hours they are all killed.

3. When sperm are added to unfertilized eggs, both being in complete absence of oxygen, fertilization does not take place, and the fertilization membrane is not thrown off because the sperm are not motile, and cannot get to the surface of the egg. The membrane is thrown off immediately on admission of air. If there is the slightest trace of air, which may leak through the vaseline seal to the chamber, sufficient for only a few sperm to be very slightly motile, the eggs with which they come in contact throw off fertilization membranes, but do not develop further until more air is admitted. If oxygen is necessary for membrane formation, it is in an almost infinitesimal amount.