1909.] 



PUBLIC DOCUMENT — No. 31. 



169 



Studies in Vaeiation. 



In our last report figures and diagrams were given to show 

 the amount and range of variation in several qualities, namely, 

 (1) length of vine, (2) number of pods per vine and (3) num- 

 ber of peas per pod. It will now be of interest to compare the 

 variation of 1908 with that shown in 1907, remembering that 

 the plants of 1908 were the progeny of those grown in 1907. 



Before taking up the figures, attention should be called to the 

 fact that the very dry summer of 1908 shows its effects very 



Fig. 3. 



plainly in these figures. Inasmuch as the crojD was grown on 

 dry, gravelly land these efi^ects of drought were intensified. 

 The length of vines was therefore much shorter, the number of 

 pods generally less and the peas per pod fewer, than in 1907. 

 This need not affect the amount and character of variations, 

 however. When the data are exhibited graphically, as in Figs. 

 1, 2 and 3, the curves of 1907 and of 1908 ought to show some 

 plain correspondence. 



