Tlie influence of temperatnre on tlie geotropic 

 presentation-time 



by 



A. A. L. RUT GERS. 



With Plate I. 



NEW VOKI 



botanicai 



Inteoduction. 



§ 1. Récent views on the influence of tem- 

 pérature on physiologie al processes. 



The influence of température on physiological processes 

 has often been the subject of investigation. Asearlyeven 

 as the beginning of the nineteenth century déterminations 

 were made of the maximum, optimum and minimum 

 températures of growth. It is especially since the resear- 

 ches of Sachs in 1860 that more and more importance 

 has been attached to thèse cardinal points of température; 

 and the curve representing the connection between a given 

 température and a physiological process (generally called 

 the optimum-curve) was thought fully' to represent this 

 connection. In the second half of the nineteenth century 

 a good many investigators hâve tried in varions cases to 

 détermine this température curve, as it was thought the 

 end would be attained in a given case, by the détermina- 

 tion of the cardinal points of température. 



This View has recently changed. 



Recueil des trav. bot. Néerl. Vol. IX. 1912. 1 



