120 DOMESTICATED ANIMALS AND PLANTS 



that is variable, and where variability can be accurately meas- 

 ured, will afford a problem in statistical determination. 



Milk and Fat from 1200 Cows in 

 Illinois Dairies 1 



Milk 



The solution of the problem on milk and fat tells us that 

 cows vary among themselves 1770 pounds of milk and over 71 

 pounds of fat per year, but that the real variability of the two 

 characters is practically identical — 32.11 and 32.90. 



References. 1. " Principles of Breeding " (chap. xii). Davenport. 

 2. " Statistical Methods." C. B. Davenport. 



1 From the records of the dairy department of the University of Illinois ; 

 data collected by Professor Fraser. 



