Genetic studies with plants and small animals have yielded considerable information of great fundamental and economic value. Dairy cattle, on the other hand, with their long gestation period, single birth, and relatively short life span, do not lend themselves to rapid progress in compiling sufficient data for sound conclusion.

This progress report is based upon Research Project No. 716, started in 1918 at the University of New Jersey by W. M. Regan, now Professor of Animal Husbandry and Animal Husbandman in the Experiment Station, Davis. The entire experiment, including the animals involved and data so far collected, was moved to the University of California in 1923.