FOLIAGE LEAVES: FUNCTION, STRUCTURE, ETC. 



29 



bubbles are numerous. That this activity holds a definite 

 relation to light may be proved by shading the vessel con- 

 taining the plant. When the light is diminished the bub- 

 bles diminish in number, and when sufficiently darkened 



synthesis. 



the bubbles will cease entirely. If now the vessel be again 

 illuminated, the bubbles will reappear, and the rapidity 

 with which the bubbles are formed will indicate in a rough 

 way the activity of the process. That this gas being given 

 off is mainly oxygen may be proved by collecting the 



