c. V. L. CHARLIER, TRTENTALIS EUROP^A. 



From these numbers I obtain 



Length (/): Mean = 7°^°^,05 ± 0,60, 

 Thickness (6): » =2 ,i8 ± 0,i5, 

 and hence 6 : Z = 0,3 1 



The dispersions were calculated through the intermediate 

 of the average deviations (compare Grunddragen p. 20), the 

 result being 



For the length: c = 2,o •/ a:M = 0,29, 

 » » thickness: a = 0,5o '.* a:M = 0,23. 



From the values of a the above values of the mean errors 

 in the mean were calculated in usual manner (=(M) = a : V^^)- 



7. Stem. For examining the length of the stem I have 

 had only to dispose of 30 samples. Ordering these samples 

 into classes with a breadth {w) of 20 mm I have obtained 

 the following frequencies (F), giving the number of samples 

 in each class: 



Length of the stem 



