Standard Deviation 



361 



corolla is concerned) these two populations are almost identical, 

 for the difference in the means of the two populations is slight. 

 However, when we look at the distribution of the corolla lengths 



TABLE 21 ^ 



The Determination of Some Statistical Constants of the Corolla 

 Length of a Family of Fi Plants from the Cross Nicotiana Langs- 

 dor ffii X N. alata 



(Based on data from East in Genetics.) 



2/F 1876 _^„ 

 X = -^^— = = 40.78 



n 



46 



= a/S = -1^ 223.90 ^ 2.2 



<r 2.20 



S.E.z = ±--p =:rir^ = ±0.32 

 y/n 6.78 



.6745(7 

 P.E.x = ± 7=^ = ±0.22 



S.E.^ = ± 



46 



tr _ 2^ 

 ^i ~ 9.59 



20 



= ±0.23 



\/n 



.6745(r ^ ^ 



P.E.^ = ± — ;=r- = ±0.15 



zn 



100(7 100 X 2.20 



V = = — — — = 5.39 



J- 40.78 



S.E.„ = ± -^ \/l + 2 (-^\ = ±0.56 

 \/2n ^ VlOO/ 



P.E.„ = ± 



.6745v 



^ VlOO/ 



38 



of these same populations in Table 19, or their frequency curves 

 as drawn in Fig. 98, we see that so far as the range of values is 

 concerned these two populations are very different, for the small- 



