28 



ASSIMILATION. 



[CH. II 



(covered with a few drops of water) and containing leaves 

 of land-plants. 



(35) Plants deprived of GO Z . 



To show that the formation of starch depends on 

 the presence of CO 2 it is necessary to cultivate plants in 

 such a way that they have access to oxygen but not to 

 CO,. 1 



Water-plants. 



Water which has been boiled and allowed to cool in a 



FIG. 7 Exp. 35. 



closed flask will be free from both and C0 2 . But if 



the flask is connected with an arrangement preventing 



1 Godlewski, Flora, 1873, p. 378. 



