inheritance; of I^ECUNDITY IN DOMESTIC FOWL. 



291 



ary and February. Taking the mean of the coefficients of varia- 

 ation for these four months as given by Pearl and Surface (37,' 

 table 5, p. 96) we get 95.15. 



TABLE 2 



Constants for variation in zvinter egg production of the Barred Plymouth 

 Rock and Cornish Indian Game breeds 



Breed 



Mean 



Standard de- 

 viation 



Coefficient of 

 Variation 





Eggs 



Eggs 



Per ce 1. 



Barred Plj'mouth Rock 



36.35 ± 1.04 



26.69 ± 0.74 



73.42 ± 2.92 



Cornish Indian Game . 



11.64 ± 0.88 



10.61 ± 0.62 



91.15 ± 8.73 







Differences 



+24.71 ± 1.36 



+16.08 ± 0.97 



• 



—17.73 ± 9.21 



Barred Plymouth Rock: 









All High Lines in 1908-091 . . 



54.16 







All High Lines in 1909-101. . 



47.57 







All High Lines in 1910-1 1' . . 



50.58 







1 Figures taken from Pearl (28) . 



The inferiority in egg production of the Gornish Indian 

 Games is most strikingly shown by the integral curves from 

 table I. In table 3 the integral curves are given (in inversed 

 form) for the winter production of Barred Rock and Gornish 

 fowls. 



The data of table 3 are shown graphically in figure 451. 



This diagram is to be read in the following manner. The 

 percentages of the flock laying a specified number of eggs are 

 plotted on the abscissal axis. The different egg productions are 

 plotted as ordinates. From the diagram it appears (for exam- 

 ple) that whereas 47 out of every 100 birds in the Barred .Rock 

 flock each produced 35 or more eggs in the winter period., only 

 4 and a fraction birds out of every- 100 in the Gornish Indian 

 Game flock were able to produce as many eggs as this — 35 — in 

 the same period. ■ 



Now in individuals which are high layers, and have this char- 

 acteristic in hereditary form, there must be involved some fur- 

 ther physiological factor in addition to the normal ovulation 

 factor already discussed. An analysis of extensive statistics has 

 shown (36, 37) that high fecundity represents essentially an 

 addition of two definite seasonal, laying cycles to the basic, nor- 



