The unidentified nutrients found in animal protein concentrates

Investigators in this field have been led to believe that the growth factor found in animal protein was vitamin-like in nature rather than an amino acid. The experiments which have furnished the data for this report were initiated in an attempt to find more conclusive evidence to answer this question. In the experiments the animal protein used was fish solubles. The fish solubles were broken down into several fractions, and these fractions, examined both as to chemical and to physical properties, were fed to chicks in order to ascertain the properties and the amount of the original growth factor they contained.