T22 



THH PHYSIOLOGY OF STOMATA. 



Conclusion. — The stomata behaved alike in the presence and in the absence 

 of C0 2 . In the absence of C0 2 , oil failed to appear in the guard-cells. 



Table 53. — Data of experiments 201a and 201b. 



Experiment 211. — March 31, 1906. Cutting placed in air deprived of CO2; potassium 

 hydrate, and lime water under bell-jar. Set up at 6 h 30 m a. m. 



6 h 30 m a. m. Normal; starch abundant in the guard-cells; very minute granules visible 

 in the chlorenchyma plastids; no oil in stomata; 2 to 6 (8) micra (plate 13, figs. 2 and 3; 

 plate 14, fig- 1). 



11 a. m. Normal; starch in chlorenchyma; little or none in guard-cells; oil; 4 to 8 

 micra (plate 13, figs. 4 and 5). 



Experimental : Moderate amount of starch in chlorenchyma, none in stomata ; oil drops 

 large; bell-jar temperature 42°C. ; 3 to 11 micra; no trace of precipitate in the lime water 

 (plate 13, figs. 6 and 7; plate 14, fig. 2). 



Conclusion. — In the absence of C0 2 the reduction of starch during the early- 

 hours of the day took place as under normal conditions. In this case oil 

 was formed also, as is true under normal conditions. As should be expected, 

 starch was not formed in the chlorenchyma in excess of the amount already 

 present at 6 h 3o m a. m., 1.5 hours after sunrise. 



