CHAPTER VIL 

 Discussion of Resuit s. 



If the results hère obtained are comparée! with those of 

 Correns, they are in so far alike that he also says that 

 for the occurrence of stimulus-movements oxygen is 

 necessary. 



Further he has pubHshed statements deaUng with the 

 oxygen-content at which the stimulation-process can still 

 just take place. Since he finds différent percentages of 

 oxygen for the perception of the geotropic and phototropic 

 stimulus, he concludes that geotropic curvatures can occur 

 with smaller quantities of oxygen than phototropic ones. 

 I cannot, with the results obtained in this investigation 

 confirm this conclusion, on the contrary, the phenomena 

 in the geotropic and phototropic stimulation-processes 

 are in ail respects pretty much alike. Àlthough I hâve 

 done very few experiments with seedlings in atmosphères 

 of low oxygen-content, thèse experiments, however small 

 in number, sufficiently point to a like behaviour. The 

 reason for Correns' conclusion lies in the fact that he 

 always worked with continued stimulations and conse- 

 quently with curvatures that were not comparable, whilst 

 moreover in that case the plants experienced a change of 

 sensibility during the experiment. For this reason I worked 

 with an equal maximal curvature of constant extent, both 

 in the geotropic and in the phototropic experiments. 



