336 THE AMERICAN NATURALIST [Vol. XLVI 



Season is evidently a large factor in determining number 

 of pods per plant. This is most striking in the means 

 but it is also detectible in the standard deviations. For 

 the means we note that in each of the four strains the 

 average was conspicuously lower in 1909 than in 1908 on 

 the H field and slightly higher in 1909 than in 1908 on the 





ANCESTRAL SERIES 



COMPARISON SERIES 



NAVV h 

 NAVY 





















- 





























■ 





\ 



Y 















■ 



< AND SERIES OF PLANT! 



1 1 s 3 | § 1 1 



















■ 































T. 















V 















FLAG. 



















■ 



























i 



















D field. The standard deviations show precisely the 

 same results for the H field, but the differences between 

 1908 and 1909 for the D crops are relatively small. 



(c) The differences between the comparison series are 

 considerable, but it is impossible to be certain of any in- 

 fluence of the treatment of the ancestors. 



