33 



Thirdly the results of xMrs. Ru tten— Pekel haring ') 

 made me foresee difficulties on this point. Mrs. Rut te n — 

 Pekelharing had been working in the same laboratory 

 under the same conditions and with the same object of 

 experiment; the following tables compiled with the aid of 

 the figures on page 261 — 266 of her investigation show 

 how far variability made itself felt: 



Angle of déviation 90°. 



Angle of déviation 45°. 



Angle of déviation 135°. 



Angle of déviation 40°. 



I too thought statistical treatment the best means of 

 overcoming this difficuity. Therefore in the beginning I 



1) C. J. Rutten-Pekelharing, 1910, p. 261—266. 

 Recueil des trav. bot. Néerl. Vol. IX. 1912. 3 



