14 



dealt further with them and hâve only alluded to them 

 for the sake of completeness. 



Lastly it should be mentioned hère, that M a i 1 1 e f e r, 

 in his paper on geotropism which appeared in 1909 and 

 also dealt with the influence of température, deduced a 

 formula for this influence from Bach's figures. 



Maillefer himself however remarks, that the figures 

 on which his formula is based were insufficient and that 

 this formula can only be used with great reserve. 



In Chapter III, in discussing my own results, the con- 

 clusions of thèse various writers will be subjected to 

 criticism. 



§ 3. Object of the présent investigation. 



When comparing what was said in § 1 about récent 

 views concerning the influence of température on physio- 

 logical processes with ourreview of the publications dealing 

 with the relation between température and geotropism, as 

 given in the préviens section, it is clear that up till now 

 thèse ideas hâve not been applied to the field of physiology 

 of stimulus. 



It is the purpose of this investigation to study the 

 influence of température on the process of geotropic sti- 

 mulation from Blackman's point of view with the object 

 of ascertaining whether the ideas developed by him are 

 applicable to this case. Hère I will briefly indicate, by 

 what means I hâve tried to attain this end. 



As measure for the influence of température the pre- 

 sentation-time was chosen, because this quantity is theo- 

 retically and experimentally the best known in the process 

 of geotropic stimulation and is moreover suitable for an 

 exact quantitative investigation. 



The reaction-time is only dealt with in so far as the 

 accounts of the experiments relating to the présentation- 



