Sept. IS, 1919 Variation in Milk of Ayrshire Cows 



307 



11 13 15 17 19 21 23 25 27 29 



MEAN WEEKLY YIELD - GALLONS 



FlC. a. — Histograms and fitted curves for variation in mean weekly milk yield of Ayrshire cows of ages 



8 to 12 years. 



