THE ABSORPTION OF CALCIUM AND PHOSPHORUS

Knowledge of the conditions and extent of the absorption of nutrient materials from the alimentary tract is essential to an intelligent understanding of many abnormal as well as normal conditions. If the alimentary utilization is poor, it is frequently desirable to know what portion of the gastro-intestinal canal or what contributory secretory gland may be disturbed in function. As a recent writer has expressed it, measurements of the proportions of the ingested food substances made available to the uses of the body by digestion and absorption are necessary to the estimation of the nutritive value of foods. They serve also as indexes of the digestive and absorptive powers of the gastro-intestinal tract in health and in disease, and of the factors influencing digestion and absorption. Studies of food utilization considered from this standpoint have heretofore involved rather laborious analytic procedures and consequently have been limited in scope and frequency. Bergeim