The determinations were made with the blood serum from the umblical cord at the time of labour and with the blood serum of mother obtained shortly thereafter, comprising some two hundreds infants and their mothers. In the infant the average percentage of inorganic phosphorus was 4.91±0.486mg., and that of total calcium was 10.41±0.699mg.: in the mother the average percentage of inorganic phosphorus was 3.10±0.333mg., and that of total calcium was 8.83±0.586mg. It is apparent that the contents of the inorganic phosphorus and total calcium in the serum of the newborn is higher than those of the mother's serum. Regarding the inorganic phosphorus content, a positive correlation was shown between the infant and its mother; this held true, though to a less extent, also for the calcium content. These suggest the existence of certain relationship between the maternal condition during pregnancy and the state of well being of the fetus. The inorganic phosphorus content of the mother's blood is more constant and has a narrow range of variation than that of the newborn.
The content of the inorganic phosphorus of the serum of the newborn tends to fall during the Winter and Spring and to rise during the Summer months. This holds true, though less marked, also for the serum of the mother. On the basis of results of the present studies, it is suggested that the lowest limit of the norml range of the inorganic phosphorus content may be regarded as about a little sbove 5.0mg. per hundred cubic centimeter of serum, and lower range than this may indicates the existence of certain faulty biochemical reaction in the fetus, such as rachitis or prserachitic state.