12 



J. ARTHUR HARRIS. 



macro- and the number of microsporophylls from their probable 

 value are the coefficients of critical value. These are also given 

 in Table III. The correlations for stamens and pistils are 

 necessarily equal in magnitude but opposite in sign. They 

 show that the number of pistils is relatively larger in the flowers 

 with larger numbers of sporophylls. The results are consistent 

 in sign throughout. All of the correlations except that for the 

 series from Trogen may be considered certainly significant in 

 comparison with their probable errors. 



While the constants for certain of the series differ significantly, 

 the results are (considering the relatively small numbers and the 

 very wide geographical distribution of the material) very con 

 sistent. Five of the eight series differ from r = .50 by less 

 than twice their probable error. Of the other three series, 

 only Professor Ludwig s Trogen material is very aberrant. 



For two of the series I have determined the standard devia- 



/6 /? 20 22 2.4 2? 28 30 32 3,4 3ff 38 40 42 4,4- 4,6 



FIG. 2. Empirical means and regression straight lines for regression of stamens 

 on pistils and pistils on stamens. Guernsey series. 



