STOPPER 



FILLING TUBE 



'\y- 



-V- 



OUTLET 



;-Si? 



—CLAY WALL 

 — -LIPOIDAL FORMATION 

 —PLASMATIC LAYER 

 —DISSOLVING LAYER 

 -CELL LIQUID 



PLANT CELL 

 WORKING MODEL 



Fig. I. Artificial cell designed to illustrate variations in outer wall and 

 plasmatic layer. The clay wall is that of a filter thimble such as is used in 

 the Livingston evaporimeter. The lipoidal layer is drawn heavily out of pro- 

 portion to illustrate more clearly the processes extending into the wall and the 

 plasmatic layer. The plasmatic layer in the experiments described in this 

 paper was composed of agar, agar-gelatine, or modified mixtures. The cell 

 was submerged to the top of the stopper in operation. 



