426 PEARL— SEX RATIO IN DOMESTIC FOWL. 



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X 



w 



00 



'OS 



'09 '10 



'11 



'13 



'14 



15 



YEAR 



Fig. I. Showing the mean c? sex ratio in consecutive years. 



III. The Normal Variation of the Sex Ratio. 

 So far we have considered only mean values. Let us now exam- 

 ine the dispersion or variation constants. From the totals of Tables 

 I., II., and III. we deduce the standard deviations set forth in Table 

 IX, by the ordinary method. 



TABLE IX. 



Standard Deviation of the Sex Ratio of the Domestic Fowl. Various 



Breeds. 



Group. ' R ^. 



Families of lo and over 13-37 + -20 



Families of 4 to 9 inclusive 24.18 + .59 



Families of i to 3 inclusive 3972 + 1.49 



Families of 4 and over 18.30 + .23 



