185 



TABLE 12. 

 Number of plants observed after 60 minutes 55. 



A comparison of thèse two tables, together with the 

 high percentage of curvatures of 2 m. m. after an obser- 

 vation time of 60 minutes, shows at once that with a 

 stimulus of 400 M.C.S. the maximal reaction for Sinapis 

 seedlings is 2 m. m. and that it reached after 60 minutes. 



If we compare the results obtained with Avena and 

 with Sinapis, the much greater variability of the cur- 

 vatures of the latter plant is at once évident and further 

 the large number of non-reacting seedlings. As against 

 289 Sinapis seedlings which gave a geotropic reaction, 

 there were 102 which did not curve, i.e. of the 391 objects 

 used 102, or 26.1 7o' did not react. In the phototropic 

 experiments 104 of the 322 seedlings remained straight, 

 i.e. 32.3 7o- Thèse figures show that we must not be too 

 ready to draw conclusions from the non-curvature of a 

 few seedlings. 



