27 



From the fact, that no gas-bubbles escaped, follows 

 that the produced oxygen was released so quickly to the 

 outside, that either the over-saturation was not attained 

 or not enough gaseous oxygen was produced to fill the 

 intercellular spaces entirely. However in any case the 

 hquid in the intercellular spaces will contain a good 

 quantity of dissolved oxygen. 



If the rate of assimilation increases by a rise of tem- 

 pérature it will cause but a small increase of the concen- 

 tration of the oxygen in the water in the intercellular 

 spaces. So the différence between the concentration of the 

 oxygen inside the Helodea-shoots and the oxygen of the 

 surrounding liquid can increase but a little or not at ail. 

 It is true, that the velocity of diffusion of the oxygen through 

 the cell-walls to the outside will increase, but the tempe- 

 rature-coefficient of this physical process is small. It is 

 not to be ascertained, whether the release of oxygen 

 through the wall into the surrounding water will be 

 influenced by raising the température. Hère, indeed an 

 évasion of the COo from the wall and an invasion into 

 the moving water takes place. Now B o h r ^) demonstrated 

 that the température-coefficient of the invasion of gaseous 

 COo in flowing water or saline solutions is small and 

 négative, but that one of the évasion of COo from a solution 

 into the air is small and positive. So it seems very probable 

 that the rate of the release of oxygen through the cell- 

 walls into the surrounding water is modified but little by 

 rise of température. 



Yet this view cannot stand for the whole explanation. 

 For, if a larger quantity of oxygen was not removed in 

 some way into the surrounding water, when raising the 

 température, the intercellular spaces would be entirely 



M Wiedemann's Ann. d. Physik u. Chemie. Bd. 62. 1897. S. 

 644. Bd. 68, 1899, S. 500. 



