A short preliminary report1 of this study was made in 1932. In a table presented at that time were shown the amounts of sodium potassium, magnesium, chlorine, nitrogen, calcium and phosphorus in the ash content of rat pups. These figures revealed that the calcium and phosphorus contents of the fetal ash were increased when the mother rat was given vitamin D. In view of the present tendency on the part of obstetricians to give pregnant mothers large doses of vitamin D for various causes, this observation becomes significant, and it seemed advisable to make a further study on a larger series of rat pups, comparing the effect of viosterol and cod liver oil on the calcium and phosphorus transmission from the mother to the fetus.
The rats used for our experimental work were raised from our stock colony. Only first litter pups were used in this study. The female