394 



THE AMERICAN NATURALIST [Vol. XLIII 



are not a random sample of the breeding flock but were 

 definitely selected to illustrate the behavior of the index. 



Table I 



Showing Eepresentative Values of the Selection Index in Poultry 



t 







i 



1 1 N 1 









L 





? 

 & 









lh i 











I" 



I 



— 





JS 





-— — 



— 



P 

















b 2 9; 

















33.33 





50.00 2.9 



12- 





If 1 









12 



11.67 





60.00 3.6 

 69.23 4.0 



122 

 375 





37.50 36 







43- 









37 50 4.2 







45^86 16 



20.00 

 22.73 



I! - 



393 



12 



26! 67 



14 





731 



61 



37.50 9 

 35-3 23 





i:u 



717 



39 













29 







13.3 

 13.3 



377 







16 













1 1.2 

 14.5 



746 



359 



59 



2-.:::; 

 39.17 



17 





19 

 1 52 





25-3 13 



7.14 





too 





:;-2.r,n 







3fil 







lY.2- 



19.6 

 20.2 









16 



io" 











12 -2 



20.3 



725 









27 27 9 1 







59' 17 6 



12.51 



303 



1 12 

 407 



41 



48.07 

 17.51) 

 41.67 



18 



4*; 



j 25 00 9.3 

 10.53 9.4 

 23 53 9.7 



74! 







5.-1 

 13.-! 



31.6 

 45.2 



From this table the following points are to be noted: 

 1. The selection index ranges in value between 2.8 and 

 45.2 in the cases chosen for illustration. These figures 

 do not represent the extreme values which may be ob- 

 tained for this index. They suffice, however, to bring 

 out the point of practical importance that the index 

 fluctuates through a wide numerical range as the value 

 of the birds as breeders changes. 



4 It should be said that all the records given in this table were made 

 ing was all done in incubators ° USlng ' ^ ^ ^ ' ^ 



