34 



great many of the individuals showing this lower mini- 

 mum value. 



Also with Anethiim graveolens a great différence is noticed 

 in the shape of the curves of the number of umbel-rays 

 in the two cultures, fig. VI. The curve of the well-fed 

 plants is nearly symmetrical, while that of the plants 

 from tbe sandy soil is asymmetrical in such a way that 

 the top of the curve lies nearer the minimum. It can 

 not be stated vv^ith certainty whether in this case we hâve 

 the same phenomenon as with Iberis amara, i.e. whether 

 the lack of symmetry of the curve indicates that it has 

 been shifted to the proximity of the lower limit. But the 

 fact that the minimum now obtained, viz. 1, is already 

 very small compared with the maximum 41 and that this 

 lower limit cannot be zéro, renders this view probable. 

 Yet we must bear in mind in cases like the présent, that 

 the appearance of an asymmetrical curve need not in 

 gênerai be a proof that the curve is located near one of 

 the limits of the range of variation, but that the assym- 

 metry of the curve may also be the conséquence ofentirely 

 différent causes. 



Ctroningen, .July 80, 1904. 



