In Reply.—I thank Dr Miller for his interesting comments on elongation of the small intestine in the prune-belly, or abdominal muscular deficiency, syndrome. There are additional data with regard to small-intestinal length with which one may study the possible effect of constraint on developing tissues. In six infants with congenital diaphragmatic hernia, the mean small-intestinal length was 39 cm shorter than normal, although within 1 SD. In two cases of omphalocele, the mean small-intestinal length was decreased by 76 cm, beyond 1 SD. Likely reasons for this tendency toward abnormal shortening seem to conflict, however. If the pleural space in diaphragmatic hernia or the omphalocele sac serve as extensions of the abdominal cavity, then there seems to be increased space in which the small intestine can develop. In this instance, one might expect elongation of the small intestine to occur, visà-vis the Miller hypothesis. Conversely, in the two malformations,