25 



Examining the figs. I — V, relating to the characters of 



Iberis amara, figs. VI — VIII of Anethum graveolens and 



XI — XIII of Malca vnlgaris it appears that, whereas with 



the two former plants the shifting of the curve is very 



différent in the varions cases, it is about the same for the 



three characters of Malva vnlgaris and for ail three of them 



relatively small. So the curves enable us to form an 



approximate idea of the influence of varions nutritive 



conditions; but a clear insight is only obtained when the 



curves are defined by definite constants and thèse are 



mutually compared. In this way it is possible to détermine 



w^hat influence feeding has not only on the médian value 



of the character, but also on its variability. In order to 



obtain thèse values, the médian value M and the quartile 



Q were deduced from the observations. From thèse the 



M 

 coefficient of variability ^, which is a measure of the 



variability and enables us to mutually compare the varia- 

 bility of différent characters, was calculated by the method 

 introduced by Ve rschaffelt '). Also for the somewhat 

 skew curves thèse values hâve been determined, since thèse 

 curves do not considerably deviate from the symmetrical 

 ones, and besides, in ail cases the average of both quartiles 

 has been taken. Only from the semi-curve for the branches 

 of the third order of Iberis amara, fig. V, no constants 

 were calculated. This curve will be dealt with later on. 



I give hère the values found for the varions characters 

 in the plants studied in the same order as that of the 

 curves of the plate. In the table, W means the constants 

 of the well-fed, B those of the badly-fed plants. For each 

 character are given : the médian value, the quartile. the 

 variability-coefflcient and the minimum and maximum 

 value. Besides the différences of thèse values in the well-fed 



1) Ed. Verschaffelt, 1. c. 



