154 RAYMOND PEARL 



this inbreeding is low, on the average, even as compared with 

 single cousin mating. 



The data from which an answer may be obtained to our sec- 

 ond and third questions are most readily had from an examina- 

 tion of the males which have been used as sires in the Station's 

 Barred Rock flock for a period of years. Since all the females 

 used as breeders within this period will be descendants or col- 

 lateral relatives of these males, we are able to form an ade- 

 quate idea of the blood lines involved in our alcohol foundation 

 stock from an examination of the males. In the following 

 resume the bird number of every male Barred Plymouth Rock 

 used as a breeder in the years 1910-1914 inclusive is given. 

 Each bird number is followed by a figure in brackets. These 

 bracketed figures show the number of times the designated male 

 appears in the first four ancestral generations of the stock used in 

 the alcohol experiments, as shown in the pedigrees exhibited in 

 the preceding pages. 



B. P. R. males used as breeders 



In 1914 



Birds Nos. 634 (2), 636 (0), 637 (2), 638 (5), 639 (1), 640 (0). 



In 1913 



Birds Nos. 619 (1), 620 (2), 621 (1), 622 (4), 623 (1), 624 (11), 625 (2). 



In 1912 

 Birds Nos. 563 (36^), 606 (9), 607 (1), 608 (3), 609 (1), 610 (15), 611 (0), 612 (1), 



613 (0). 



In 1911 



Birds Nos. 563 (36), 564 (6), 587 (10), 588 (20), 589 (1), 593 (3), 595 (3), 597 (0), 



598 (16), 599 (12). 



In 1910 



Birds Nos. D31 (1), 552 (0), 554 (2), 562 (1), 563 (36), 564 (6), 566 (1), 567 (4), 



569 (3), 573 (1), 574 (3). 



From the above data it will be seen that of the 40 Barred 

 Plymouth Rock males used as breeders in the general popula- 

 tion in the years 1910 to 1914 inclusive, thirty-four, or all but 

 six (Nos. 552, 597, 611, 613, 636, and 640) are represented in the 



^ In this and other cases where the same male was used in successive years 

 the number in brackets is the total number of occurrences regardless of genera- 

 tions, just as in the cases where the male was used during one year only. 



