A STUDY OF THE DIFFUSIBLE FACTOR RELEASED BY THE JELLY OF THE EGG OF THE TOAD, BUFO ARENARUM

Some properties of an essential factor for fertilization released from the oocyte strings of the toad, Bufo arenarum were studied. All the experiments were carried out with a partially purified preparation of this diffusible factor, and the general procedure consisted in assaying under different conditions its capacity to recover the fertilizability of oocytes previously deprived of this active substance. Using this procedure, a test was devised for estimating the diffusible factor activity. As regards the mechanism of action of this fertilization factor the data reported here are not consistent with the previous assumption that the factor plays its role in fertilization through a simple pH rise of the inseminating medium. Treatment of the gametes with the diffusible factor before insemination proved to be ineffective to promote fertilization; the factor must be present at the very moment of insemination.