144 A MANUAL OF MENDELISM 



As yet only one breeder with a herd large enough and 

 records kept for a long enough time has been found. 

 The records of his herd corroborate the Danish evidence. 

 Sires were found having high-grade and medium-grade 

 daughters, or medium and low grade, or of all three 

 grades. The following table shows the grades which 

 the daughters of five different sires fell into as judged 

 by their maximum yields after their first calving : 



Maximum Daily Yields 



30 to 40 lb. 20 to 30 lb. 13 to 20 lb. 



A's daughters 8 10 — 



B's daughters - 18 10 



C's daughters 6 24 4 



D's daughters 4 11 7 



E's daughters 3 14 6 



The headings "30 to 40 lb." and so on indicate 

 considerable fluctuations, caused no doubt by a number 

 of factors having smaller effects which remain to be 

 searched for in the future. 



