82 



ii M-Wi B Üi @ 5i "-^ «: ft" .^Ji I'l'J m % 



I'iy- 3- Ctadoi^natJnti inclhui/nSy Molsch. female. 

 Surfan: view, f^ivin^ 2 exlreme variates of population. 

 n, largest 34 iimi ; /i, smallest 24 mm form. (Natural 



si/,e). 



■ \ll '333 female beetles were f^roiiped according 

 til till- units of tlie scale used in case of the 

 111 iK's and \vc obtained 12 classes as follows 

 (Tabic 2). 



Tabic 2. 



Class (nun) 23 24 25 26 27 28 29 30 31 32 33 34 

 Freciucncy 9 19 61 129 187 224 226 221 163 68 21 5 



From this tabic (fable 2) wc can Leather 4 important facts, as the follow- 

 ing descriptions show. First, the indi\-iduals standiiii; at both the extremities 

 are far inferior to tiic males in bod)- length, as can be seen at once by com- 

 paring tabic 2 with tabic I.' .Second, the variation in this respect passes over 

 from each unit to the adjacent ones not abruptly as in the males, but fluc- 

 tuating contiiuiousl}-; accordingly, its range is shorter than in the case of males. 

 Third, there are, in consequence, only 12 classes instead of 23 as in the 

 males. Lastl)', the number of indi\iduals in each class increases suddenly 

 towards the high tjpes and then decreases likewise suddenly. 



These data can be represented graphically by a curve which is shown in 

 Fig. 4. 



The curve starts at first rather slowly and ascends suddenly from 26mra 

 to 28mna ; then it slowly attains the mode and descends likewise slowly to 

 30mm which is at about the same height as 28mra on the opposite limb. 

 From this point to 33mm it descends steeply just as the opposite limb ascends. 

 Then it slides into the high type. 



Both limbs of the curve, as is evident from Fig. 4, are nearly symmet- 

 rical and the curve is unimodal having an apex at 29 mm. It follows tliat 

 the mean value of the variates, 28.6mm, nearly coincides with the empirical 



