This study is a continuation of the investigations of Prof. Agar, Professor of Zoology, University of Melbourne, entitled “Heredity and milking function,” which appeared in the Journal of Agriculture of Victoria in January, 1926; and it deals with the inheritance of milk, butterfat percentage, and butterfat in the Victoria Stud of Red Poll Cattle owned by the Department of Agriculture of Victoria, at the State Research Farm, Werribee. The milk and butterfat records used in these investigations are the 273 day records performed under the regulations governing the Victorian Government Pure-bred Herd Test, published annually, and included in the successive volumes of the Red Poll Herd Book of Australia. They cover the period since the establishment of the Government Herd Test—1912–13 to 1929–30.