Recueil des trav. bot. Néerl. Vol. XIII. 1916. 



Tab. II. 



0.70 0.80 Q90 1.00 1,10 120 



Fig. 2. Observed frequency curves (art. 2). 



130 



-0.30 -0.20 -QiO +Q10 +0.20 



Fig. 3. Theoretical normal curves (art. 2). 



+ 0.30 



