STUDIES of malnutrition indicate the importance of the "sparing effect": of all organs of the body, the brain is least affected by starvation during growth.1-5 This widely accepted but partially correct conclusion is based on observations of rats weaned at 21 postnatal days and then undernourished. In 1917 and 1918, Sugita6,7 emphasized that the normal growth of the cerebral cortex of the rat is precocious in relation to the body; the cortex reaches adult width and develops six layers during the first three weeks of life, but the maximal increment of growth of the body occurs between three and seven weeks. Sugita therefore suggested that the effect of undernutrition on the development of cerebral cortex is better studied in suckling rats during the first three postnatal weeks when growth of cortex and cytoplasmic differentiation of neurons is maximal.8
Recent investigations9-11 on growth of whole