H. G. McGrath and M. E. Charles, symposium co-chairmen. L. J. Spillane and H. P. Leftin, symposium co-chairmen. C.E. Crouthamel and H.L. Recht, symposium chairmen. Norbert A. J. Platzer, symposium chairman. Stanley A. Hall, symposium chairman. Roger S. Porter and Julian F. Johnson, symposium chairmen.