MUTANTS AND HYBRIDS OF THE OENOTHERAS. 



45 



the ratio of width to length as a measure of leaf- form would not allow 

 us to infer from such overlapping that the two species are not abso- 

 lutely distinct with respect to the form of the leaves. This fact will 

 become convincingly apparent upon reference to Plate XXII, in which 



25 " "30 35 40 45 50 "55 



Fig. 8. Variation in ratio of width to length in the leaves of Onagra 

 rubrinervis and O. lamarckiana, expressed in per cents. 0. rubrinervis: 

 Range, 20-48; M., 30.077 0.084 ; <t, 3.098 0.056 ; C. V., 10.30 0.20 per cent. 

 O. lamarckiana : Range, 28-53 ; M.. S9.961 0.123; o-, 8.811 0.087; C. V., 

 9.58 0.22 per cent. 



are contrasted the leaves from the specimen of 0. lamarckiana having 

 the minimum mean ratio and those of the specimen of 0. rubrinervis 

 having the maximum mean ratio. According to this statistical meas- 



