THE exact nature of the change that occurs in the protein of the soybean as a result of cooking has been a subject of study for many years.Osborne and Mendel (1917) described experiments with rats which showed that the protein of raw soybeans would not support appreciable growth. Cooking ground raw soybeans was effective in converting the protein into a form that stimulated normal gains. In 1932, Vestal and Shrewsbury, using both rats and pigs as experimental animals, confirmed the findings of Osborne and Mendel. They attributed the improved growth to an increased food consumption and slight increase (4 percent) in digestibility of the cooked soybeans. Earlier (1930) Robison reported the results of pig feeding trials and presented evidence to show that cooking the soybean increased its value as a feed.Hayward, Steenbock, and Bohstedt (1936) determined with rats the nutritive value of raw soybeans and several experimentally produced .