1. After a preliminary trial with Shorthorn cows in Berkshire, some 461 Friesians were measured in Minnesota, U.S.A., and an attempt was made to correlate 19 measurements with milk yields.
2. Significant coefficients of correlations were obtained for:
Length from withers to hooks and milk yields;
Height at hooks and milk yield; Height at pins and milk yield;
Circumference of chest and milk yield;
Circumference of barrel and milk yield;
Area of milk wells and milk yield.
3. Correlation coefficients that were almost significant were obtained for:
Width at barrel and milk yield;
Width at hooks and milk yield.
4. The best producing cows had the largest milk wells. This was not because they were the biggest cows, for there was practically no loss of coefficient of correlation for milk yield and size of milk wells when the partial correlation for area of milk wells and yield was calculated with height at hooks held constant.
5. Evidence is presented which shows that the areas of milk wells do not increase with mere skeletal growth of cows over 4½ years old, but with increased milk production. This fact makes the area of milk wells a still more reliable indicator of milk-producing power.
6. The results obtained confirm the value of some of the points which stockmen have considered in judging dairy cows. They emphasise the necessity for considering all the points together, but indicate that certain points deserve special consideration.