Iodine Compounds and Fertilisation

Abstract

ABSTRACT It has been shown (Carter, 1931 b) that eggs of Echinus esculentus and E. miliaris which are being washed in a current of sea-water remain fertilisable for a longer time if thyroxine is present in the water of the current. In his investigation of the egg secretions and the part they play in the fertilisation of the egg, Lillie (1914) showed that the rapid decay of echinoderm eggs exposed to a current of sea-water is due to the diffusion of the secretions from the surface of the eggs, and particularly to the loss of one component of the secretions which is essential to the activation of the eggs (“fertilizin”). In view of his work, the results of the previous paper strongly suggest that the manner in which thyroxine acts in prolonging the life of washed eggs is by penetrating the surface of the eggs and causing a change in the cytoplasm by means of which the supply of fertilizin within the egg is maintained for a longer time. The probability that it acts in this way is increased by the evidence given in the earlier papers of this series (1930, 1931 a), where it was shown that the egg secretions and thyroxine act so similarly in other phenomena that it is probable that thyroxine is chemically related to some substance present in the secretions. If this conclusion is accepted, and if the substance to which thyroxine is related is fertilizin itself (and further evidence that this is so will be given in later papers), it is not improbable that thyroxine may definitely replace the fertilizin in the cytoplasm, presumably by being itself transformed into this substance by the activity of the protoplasm.