68 



convenience sake we say the presentation-time foUows 

 this law. If we ask what conclusions can be drawn from 

 this fact regarding the nature of the perception-process, 

 we hâve to acknowledge that it does not allow of any 

 certain conclusions being drawn. 



The only conclusion we can draw is that the presentation- 

 time in respect of température dépends upon a chemical 

 process, which follows van 't Hoff's law; that this 

 process is identical with the perception by no means' 

 follows. 



Discussing further the nature of this process we hâve 

 before us several possibilities, among which we can make 

 no choice. One could think perception itself to be this 

 process, so that perception would take place by means of 

 gravity directly influencing a chemical reaction, but I 

 cannot conçoive how this could take place, nor do I think 

 it very probable. Secondly we could take our starting-point 

 in the statolith-theory. I do not say I think the statolith- 

 theory to be right, my only object is to show that thèse 

 facts can also find an explanation by this line of thought. 

 Then our argument runs as follows: Perception needs 

 starch-grains and the stimulus will be greater when the 

 number of starch-grains is greater, if we suppose stimu- 

 lation to be proportional to the number of starch-grains. 

 Formation and solution of starch-grains are chemical 

 processes, and it may be possible that the formation of 

 starch-grains increascs with a rise of température, and 

 does so according to van 't Hoff's law. At very high 

 températures on the contrary the solution of starch-grains 

 should increase rapidly. The observations of Haberlandt 

 at low, and of Francis Darwin at high températures, 

 mentioned in § 2, could also be explained very readily in 

 this way. 



Thirdly we could imagine enzymes coming into play. 



