Volume IX is part of a series devoted to current symposiums in the field of biology. It contains four papers on the actions and metabolism of sex hormones, and four papers on hormonal factors in the inversion of sex.
Prof. Carl Moore, of the University of Chicago, presented the biologic introduction to the symposium on sex hormones. No one is better qualified to do this. It is his opinion that the testes and ovaries can be regarded as the principal, although not the exclusive, source of androgens and estrogens. These hormonal substances carry the principal responsibility for inducing the functional maturity of the male and the female complex, including the structural portions of the reproductive system, as well as the psychic or behavioral reactions. A specific genetic constitution to some extent different in the two sexes provides the background or framework on which the hormones operate. It has been abundantly