We had reached this status some time before 1911. But, a short time before this, there had arisen a controversy as to the relative value of different types of proteins. The animal- vs. vegetable-protein controversy was one of the side shows of this affair. This controversy had led to a careful study of the different kinds of proteins that are found in foodstuffs. Through a brilliant series of chemical investigations for whose description we haven't time or space here, chemists had shown that every protein was built up of a collection of acids which were different in structure and properties, that there were some seventeen of these in all and that any given protein might have present all seventeen or be lacking in one or more and that the proportions present varied for every type of protein. It was then obvious that proteins could not be considered as identities. More than that, it was the necessary task of the food expert to separate all proteins into their acids or building stones and not only show what was present and how much but determine the rôle each played in the body. To this task many set their faces and hands. From the results there has accrued much progress in the evaluation of proteins but an unexpected development was the part played by these investigations in the story of the vitamines. About 1909-1910 Professors Osborne and Mendel under a grant from the Carnegie Institution began a detailed investigation into the value of purified proteins from various sources. In their experiments they used the white rat as the experimental animal and proceeded to feed these animals a mixture consisting of a single purified protein supplemented with the proper proportions of fat carbohydrate, and mineral salts. Since the food furnished was composed of pure nutrients and always in excess of the appetite of the rat the necessary number of calories was also present. These researches were published as a bulletin (No. 156) by the Carnegie Institution in 1911, the same year that Funk announced his Vitamine discoveries. It was timely in this respect for one of Osborne and Mendel's discoveries was that no matter how efficient the mixture in all the requirements then known to the nutrition expert, the rats failed to grow unless there was added to the diet a factor which they found in milk. In searching for this factor they made a still further discovery for on fractioning the milk they soon learned that the unknown factor was distributed in two different parts of the milk, namely in the butter fat and in the protein free and fat-free whey. The absence of either milk fraction was sufficient to prevent growth. The 1911 publication merely described these results without attempting to explain the nature of the growth producing factors but the vitamine hypothesis of Funk naturally suggested to these authors that their two unknown factors might be similar in nature to his beri-beri curative factor and their announcement may be