29 



number of lobes of the flrst leaf of Scandix Pecten-Veneris 

 is 4- 0.08, whereas it is + 0.17 for the number ofumbel- 

 rays of the same plant. 



From what précèdes it will be seen that the influence 

 of nutrition on the médian value of différent characters 

 of the same plant varies greatly, some organs being very 

 sensitive for différences in nutrition, others experiencing 

 little différence in their development on this account. 



Concerning the value of the quartile the table shows 

 that we do not obtain in ail the cases studied, a varia- 

 tion in the same sensé by bad nutrition, as was the case 

 with the médian value. In some cases Q is greater in 

 the plants from the fertile soil, in other cases it is smaller, 

 as great or nearly as great as with the plants from 

 meagre soil. In order to be able to compare the variabi- 

 lity of the characters in both cultures, however, and to 

 draw conclusions from this comparison about the influence 

 of nutrition on the degree of variability, we mustnottake 



the quartile but the variability-coeffiicient ~, 



If, to begin with, we consider the value of this varia- 

 bility-coefficient in the varions cases, we see from the table 

 that it varies between wide limits 0.044 and 0.36. Also 



Verschaffelt ') found equally divergent values of -^ 



for the characters of différent plants studied by him. The 

 smallest variability is found with the différent characters 

 of Malva vulgaris, as well in the well-fed as in the badly- 

 fed plants. Hence this plant appears to be little variable. 

 Comparing the variability of the différent characters of the 

 same species with each other, we see that they diverge 

 relatively little with the well-fed plants, as well with Iberis 

 amara, as with Anethum graveolens and Malva vulgaris. 



1) Verschaffelt 1. c. p. 353. 



