26 MUTATIONS, VARIATIONS, AND RELATIONSHIPS OF THE OENOTHERAS. 



while that in the leaf 

 ratios was toward iden- 

 tity, as will be readily 

 seen on referring to fig. 

 6, which shows a much 

 more complete over- 

 lapping than do the 

 corresponding curves 

 for 1904. In other 

 words, since this ratio 

 was taken as a measure 

 of leaf-form, the form 

 of the leaves of O. 

 rubrinerms in the latter 

 year was but slightly 

 different from that of 

 the parent species, ex- 

 cept in those minor 

 details which were 

 pointed out in the 

 earlier study as pre- 

 venting the ratio be- 

 tween length and 

 width from being a 

 correct measure of 

 form. The lack of 

 homologyinthe leaves 

 measured in the two 

 species takes away all 

 20 25 30 35 40 45 50 significance of these 



FIG. 5. Comparison of leaf -width of Oenothera lamarckiana (broken curve) facts Ul their bearing 

 and O. rubrinervis. on the question of the 



regression of 0. rubrinerms. The constants of the several curves representing 

 the variation in leaf measurements may be compared in the following table : 



