ABSTRACT
The results given in the previous papers of this series (1930, 1931 a, b, 1932 a, b) have shown that thyroxine, and, to a much smaller extent, certain related iodine compounds, resemble the egg secretions of E. esculentus and E. miliaris in their action upon the eggs and sperm of these species and that this resemblance extends to several distinct phenomena. The conclusion has been reached that the secretions contain a substance which is not only similar to thyroxine in its physiological action but is also chemically related to it. Further, the evidence has led to the conclusion that this substance is the component of the secretions which is essential to the activation of the egg, and is therefore the fertilizin of Lillie (1914).
The probability that an active extract may be obtained from eggs is increased by the resulta of Fuchs (1915). Using simple methods he found that a water extract of the eggs of Crona was effective in activating the sperm.
I am greatly indebted in this work to Mr A. P. Orr of the Marine Laboratory, Millport, Scotland, by whom the preparation of the crude extracts of the dried ovaries and testes was earned out.
