Analytical 



Went says: "The only work involved in this method is the 

 making up of the dilutions and the splitting of the peas; the 

 estimation of the reaction is done at a glance." 



The curvatures can also be classified. Went's scheme is: 

 Degree of reaction Appearance of Split Stems. 



No auxin reaction, both halves concave at 

 the outside over their whole length. 



(as A, Fig. 6.) 



1 Slight auxin reaction, trace of convexity 

 in limited regions. 



2 Definite auxin reaction, ends of both 

 halves approximately parallel. 



3 Fair auxin reaction, ends bent inwards. 



(as B, Fig. 6.) 



4 Strong auxin reaction, ends just touching. 

 e Very strong auxin reaction, both halves 



crossing at end. 

 6 Very strong auxin reaction, halves cross- 



ing midway or at base (as C, Fig. 6). 



A 



B 



Curvatures in split sections of pea 



Fig. 6. (After F. W. Went, (1934) )• 

 stems, immersed in : 



B Tn/ C, auxin-containing solutions producing curvatures of degrees 3 

 (fair) and 6 (very strong) respectively. 



With acknozvledgments to Dr. F. W. Went and to the Editors of the 



Verslag. Kon. Akad. Wet., Amsterdam. 



131 



