1. Iron deficiency was induced in albino rats by a milk-powder diet. Control groups were given milk powder plus an iron source.
2. The haemoglobin content of the blood was determined once each month. When the haemoglobin level fell to 10 g/100 ml or less in the deficient animals, determinations were made of the vitamin C content of 24 h urine as well as of liver, kidney, adrenals, brain and blood. Additional studies were made of in vitro synthesis of the vitamin by liver homogenate.
3. The urine and tissues of the deficient animals were found to have a higher concentration of the vitamin than those of the control animals. The difference in enzyme synthesis was in the same direction, but was not statistically significant.
4. The results are interpreted as suggesting an increased requirement, by rats, of the vitamin in iron deficiency; this increased requirement is met by increased synthesis.