THE ABSORPTION OF PROTEIN WITHOUT DIGESTION

The purpose of the experiments reported in this paper is to determine whether it is possible for a protein to be absorbed through the epithelium of the gastro-intestinal tract and appear in an unaltered form in the circulating blood. This question is not a new one in the physiology of digestion. It has been studied by many workers who have employed a variety of experimental methods. Most of the experiments now quoted in the literature were made before the biological specificity of protein was recognized. It is obviously impossible to distinguish sharply between closely allied animal proteins by purely chemical reactions, such as the measurement of the content of nitrogen, phosphorus, sulphur, or by means of the salting-out methods. The newer biological methods, such as the precipitin and anaphylactic reactions, have a high degree of biological specificity, and enable one to distinguish sharply between proteins so closely related as the