Dr. Mapes, members of the Academy, and quests. It is a great privilege for me to stand here as a recipient of this award and to tell you about some of the work I have been involved in during the past 6 years. Before I begin, however, I should like publicly to thank a number of people without whose guidance or direct help none of the work would have been accomplished. My teachers have been many, but four I think have instilled in me the scientific principles and experimental training which are so necessary in any project: Samuel Z. Levine who started my pediatric training; Norman Kretchmer and Robert Greenberg, who gave me the scientific and experimental training necessary for independent investigation; and Wallace McCrory who provided the proper conditions and atmosphere in which to carry out the work. In addition, I have had the good fortune of an association with individuals throughout the world who have contributed to these studies. Professor Julio Meneghello and his whole department at the University of Chile in Santiago, Dr. John Waterlow, and Drs. Elsie Widdowson and Richard Barnes have all provided me with materials to study, as well as ideas for me to explore. Perhaps more than any, however, I should like to thank the people in my own laboratory. These include Drs. Irving Fish, Robert Karp, Elba Velasco, and finally Pedro Rosso who was invaluable to our work in Chile and who is now continuing his work in New York. A special mention, of course, must be made of Dr. Jo Anne Brasel who has recently combined her expertise with our laboratory staff and who has been an indispensable collaborator during the past 2 years.