12 



Thus Czapek found that the prosentation-time and the 

 reaction-time change at low and at high températures, 

 but at températures between 15° C. and 30° C. they 

 appear to be independent of température. 



In 1907 Bach made a similar séries of déterminations 

 for seedlings of Vicia Faba and found a much greater 

 dependence on température, as is shown by the follo- 

 wing table: 



Vicia Faba, seedlings. 



The conduisions, drawn by Bach from this table are 

 the following: 



1) With regard to their length the presentation-time 

 as well as the reaction-time show a very marked, regular 

 dependence on température between 14° C. and 35° C. 



2) This dependence is of the same kind for presenta- 

 tion-time and reaction-time ; from 14° C. upwards there is 

 a decrease with a minimum at 30° C. and afterwards 

 again a rise in presentation-time and reaction-time. 



Bach was not able to explain the différence between 

 his results and those of Czapek. 



Besides thèse investigations, extending over a séries of 

 températures, papers are to be found hère and there in 

 the literature, dealing with the influence of a deflnite 

 température on geotropic phenomena. 



