THE fate of the premature infant l depends on a number of factors, among which are the health of the mother during pregnancy, the degree of the infant's immaturity at birth, and the care that is received by the infant after birth. Methods of caring for premature infants have been determined largely on a trial-and-error basis rather than on a scientific one. The lack of adequate study and evaluation of such methods from the clinical and the experimental points of view has been due largely to the lack of realization of the magnitude of the problem and of the results that may be expected when increased efforts are made to reduce the mortality among premature infants. It is true, of course, that infants weighing at birth less than 1,000 gin. (2.2 lb.) rarely survive. Since weight in itself is not an exact measure of maturity, this criterion should not be used alone to judge viability. Some obstetricians state that an infant weighing less than 1,500 gm. is "previable."' There are, however, a large enough number of records of the survival of infants weighing at birth less than 1,500 gin., and even less than 1,000, to warrant efforts to save such infants,