4 6 



MUTANTS AND HYBRIDS OF THE OENOTHERAS. 



ure, these two lots of leaves are the most nearly identical in form of any 

 two plants, belonging to these two species, which were investigated. 

 If to the difference of outlines as shown in the plate could be added the 

 marked crinkling of the lamarckiana leaves, a character which disap- 

 pears on pressing, the discontinuity would be even more obvious. 



Interpretation of statistical results. — In reviewing the results of this 

 study one feature stands out prominently, which appears to the writer 

 to be of more fundamental significance than the mere determination of 

 the differences in superficial characters of the several species under 

 consideration. This feature will be apparent upon a comparison of 

 the coefficients of variability throughout. 



85-87 8S-90 91-93 94-96 97-99 100-102 103-105 106-108 109-111 112-114 115-117 



Fig. 9. Variation in the mean length of leaves in Onagra rubrinervis and O. la- 

 marckiana. Curve for O. rubrinervis shaded with lines rising to the right. Range, 

 O. rubrinervis, 86.28 to 107.15 mm. ; O. lamarckiana, 88.42 to 112.32 mm. 



The variability of the mutant is significantly higher than that of 

 Onagra lamarckiana in four of the six characters considered. In the 

 number of lateral branches, one of the remaining two characters, the 

 excess in favor of . lamarckiana is far within the probable error, and 

 therefore has no significance. Only in regard to the leaf-length of 0. 

 rubrinervis is there a significantly higher variability in O. lamarckiana 

 than in its mutant, and this is a character in which the mutant pre- 

 sents no material difference from its parent, the difference between 

 the mean lengths of leaves in the two species being only i.i mm. in 

 excess of the sum of the probable errors. 



Probably related to the same causes which determine this greater 

 variability of the mutants is the fact that there is a lower degree of 

 correlation between the length and breadth of the leaves of 0. rubri- 

 nervis than in 0. lamarckiana. Correlation tables of these two charac- 



