26 



coefficient is found. As a rule this even amounts to a 

 value between 2 and 3, as in most chemical processes. 

 By this circumstance it becomes very improbable that we 

 really did détermine the velocity of the assimiiation-process 

 itself. This is almost certain when we see nearer at the 

 processes taking place in the H e Iode a -shoots during the 

 experiments. 



When those shoots are washed for some time with the 

 water prepared in the way mentioned above, which con- 

 tains no oxygen nor nitrogen and which is not saturated 

 with COo, then ail the gas in the intercellular spaces will 

 be replaced by liquid. When light is thrown on it the 

 protoplasm surrounding the grains of chlorophyl will first 

 be saturated with oxygen and after that the cell-walls will 

 be entirely or partly imbued with it. Through thèse walls 

 the oxygen diffuses, partly directly to the outside, where 

 it is carried off by the streaming water, partly to the water 

 in the intercellular spaces, which is at rest. Now at a 

 somewhat active assimilation this water may be saturated 

 with oxygen. 



If the surrounding water was not moved and if the 

 water that is used had not been as free of oxygen as it 

 is now, the diffusion of the COo into the inside would be much 

 quicker than the diffusion of the oxygen to the outside 

 into the surrounding water (the diffusion-velocities in water 

 being in a proportion of 24 : 1, according to Exner). 

 This quicker diffusion would soon cause a saturation of 

 the water in the intercellular spaces (connected with each 

 other) followed by a libération of gaseous oxygen which 

 at last would escape through the eut end of the shoots. 



In other words: hère we would come again to the 

 method of counting the liberated gas-bubbles, for the 

 appréciation of which Kniep') gave such correct views. 



1. c. 



