one of the eight cows that did not receive salt died, Carlyle discontinued the experiment, and all of the remaining cows were given salt in order to restore their health. William Henry, who became Dean of Agriculture in 1901, finally gave Babcock permission to perform the single-grain experiment. Carlyle approved the experiment with only two cows. One cow was fed corn, while the other was fed rolled oats and straw with the expectation that the experiment would last one year. Three months into the trial, the oat-fed cow died, and Carlyle halted the experiment to save the other cow's life. The result was not published, mainly because Babcock had not recorded how much of each grain the cows had consumed. In 1906, a chemist from the University of Michigan, Edwin B. Hart (1874-1953), was hired by Babcock. Hart had previously worked at the New York State Agricultural Experiment Station and had studied physiological chemistry under Albrecht Kossel in Germany. Both worked with George C. Humphrey, who replaced Carlyle as animal husbandry professor, to plan a long-term feeding plan using a chemically balanced diet of carbohydrates, fat, and protein instead of single-plant rations as had been tried in Babcock's earlier experiment. The "single-grain experiment" was thus born in 1907. From May 1907 to 1911, the experiment was carried out with Hart as director, Babcock providing the ideas, and Humphrey overseeing the welfare of the cows during the experiment. Elmer McCollum, an organic chemist from Connecticut, was hired by Hart to analyze the grain rations and the cow excrement. The experiment called for four groups of four heifer calves each, and three groups were raised and two pregnancies were carried to term during the experiment. The first group ate only wheat, the second group ate only bran, the third group ate only corn, and the last group ate a mixture of the other three. In 1908, it was shown that the corn-fed animals were the most healthy of the group, while the wheat-fed groups were the least healthy. All four groups bred during that year, with the corn-fed calves being the healthiest, while the wheat and mixed-fed calves were stillborn or later died. Similar results were found in 1909. In 1910, the corn-fed cows had their diets switched to wheat and the non-corn-fed cows were fed corn. This produced unhealthy calves for the formerly corn-fed cows while the remaining cows produced healthy