justly considered a point of junction of nutrition theories with the vitamine hypothesis. The peculiarity of butter fat as a growth stimulus had been considered from another angle by a German worker, Stepp. In 1909 this student of nutrition had tried to estimate the importance of various types of fats in the same way that was later done with proteins, to determine whether, like proteins, the quality of the fats varied in nutritive efficiency. His experiments were also conducted with white rats and the main outlines of his methods and observations were as follows: Rats fed on a bread and milk diet grew normally. If now the bread and milk mixture was extracted with alcohol-ether the residue was found to be inadequate for growth or maintenance. Stepp assumed that this failure could naturally be ascribed to the removal of the fat by the alcohol-ether mixture. To determine the efficiency of different kinds of fats he then proceeded to substitute in combination with the alcohol-ether extracted diet amounts of purified fats corresponding to what was removed by the alcohol-ether. The results were totally unexpected for _none_ of the purified fats substituted were adequate to secure growth! When, however, he evaporated off his alcohol- ether from the extract of the bread and milk and returned that residue to the diet, growth was resumed as before. The conclusion was obvious, viz., that alcohol-ether takes out of a mixture of bread and milk some factor that is necessary to growth and that factor is not fat but something removed by the extraction with the fat. These results led Stepp to suspect the existence of an unidentified factor but he was unable to identify it as a lipoid. He makes the following statement which is now significant: "It is not impossible that the unknown substance indispensable to life goes into solution in the fats and that the latter thereby become what may be termed carriers for these substances." These studies were published between the years 1909 and 1912 and were therefore concurrent with those of Funk and Osborne and Mendel.