Marshall: Holstkin Milk Yikld 



439 



tion and the further objection as to 

 environmental influence upon total pro- 

 duction is removed in a further study 

 relating entirelv to per cent, of butter- 

 fat. 



In the second part of the study of this 

 case there were taken 126 record cows 

 having record granddaughters through 

 both sons and daughters. The number 

 of granddaughters is 340 through pater- 

 nal descent and 340 through maternal 



descent from 126 common grandams. 

 Each grandam was represented by not 

 less than one nor more than six grand- 

 daughters in either line. Here also 

 the ages of granddaughters and grand- 

 ams in one line corresponded closely 

 with those in the other line. The 

 means, standards of deviation and 

 coefficients of correlation in this case of 

 common grandams were as follows : 



Paternal Descent 



M: %Fat 



Granddaughters 3.52 



Grandams 3.51 



Maternal Descent. 



Granddaughters 3 .60 



Grandams 3.51 



The difference between .155 and .157 

 does not indicate any difference between 

 transmission of the character of percen- 

 tage of butter-fat in the milk, through 

 males and females. The impression to 

 the contrary, held by some cattle 



breeders, is probably based upon specific 

 instances in which the bull used was 

 more strongly bred than were the cows 

 with which he was mated and unusually 

 prepotent on that account. 



