Cross fertilization with the sperm of Arbacia lixula

Abstract

1. 1. Experiments on cross fertilization were carried out with the eggs of Paracentrotus liuidus and the sperm of Arbacia lixula. The per cent cross fertilization was greatly increased when the fertilization medium contained a mixture of Arbacia egg water and glycine. Egg water alone or glycine alone had much less effect. Crystalline serum albumin had an effect similar to that of glycine, α-alanine was also effective, but β-alanine had no effect at the concentrations used. 2. 2. A combination of certain low concentrations of sodium periodate and Arbacia egg water also increased the per cent cross fertilization. Higher concentrations of sodium periodate inactivated the egg water. 3. 3. Pretreatment of the gametes with either glycine or NaIO 4, followed by fertilization in the presence of egg water, did not result in as high percentages of cross fertilization as in the case of fertilization in the presence of glycine and egg water or sodium periodate and egg water. 4. 4. Very little cross fertilization occurred in the presence of egg water alone at a pH of about 8 or below. At a more alkaline pH (8.7), a relatively high percentage of cross fertilization occurred. A combination of egg water plus glycine or egg water plus sodium periodate increased the per cent cross fertilization at pH values below 8, indicating that this effect is independent of alkaline pH. A combination of egg water and ATP did not increase the per cent cross fertilization at pH values below 8.