174 



We see indeed that the extent of the curvature is 

 considerably greater than after 60 or after 70 minutes, 

 while from the high percentage of curvatures of 2 m. m. 

 we may draw the conclusion that the maximal reaction 

 is 2 m. m. This occurs after 65 minutes, so that for the 

 maximal curvature of 2 m. m. the reaction time amounts 

 to 65 minutes. 



B. Phototropic experiments with Avena seedlings. 



The strength of stimulus selected was 40 metre-candle- 

 power-seconds (M.C.S.). As was stated above I had to 

 illuminate the seedlings with my lamp for 8 seconds. After 

 the exposure, they were again rotated on the clinostat 

 axte and after various intervais from the beginning of 

 stimulation the extent of curvature was determined in the 

 same manner as under A. 



TABLE 4. 



Strength of stimulus 40 M.C.S. Température 20° C. 



