26 



Journal of Agricultural Research voi. xvn.No. r 



it must cover an average of a large number of individuals at one period, in order to be 

 representative. 



When the average percentages of fat for the five lactation periods of 

 each ewe are determined and compared, the variation of fat content is 

 not so marked, which indicates clearly the value of a number of tests 

 rather than one single test on an individual. 



Table II. — Average qtianiity and composition of milk for each ewe and for each breed 



Tables II and III are given for convenience of comparison of the aver- 

 age yield and the average analysis of the milk for the 50-day period. 

 Table II gives the averages for the three individual ewes of each breed, 

 and the average of these averages is represented in Table III as the 

 average for the breed. 



