The case of Bruce J. is taken from a longitudinal multidisciplined study of individuals from before birth to maturity. A research staff upon which many disciplines are represented studies the same children at frequent intervals, measuring many aspects of growth, maturation, and environment at different sequential developmental levels. The study is designed to produce a better understanding of various individual patterns of growth and maturation, and to further knowledge of the inter-relationships of such patterns and of the factors which may modify them. Some of the more important factors measured are:--

(i) The health, nutrition, and body chemistry of the mother during pregnancy.