STOMATA AND THE SPECTRUM. Ill 



Experimental part: Starch in guard-cells as abundant as in the blue-violet test, and as 

 abundant as in the control; abundant in the chlorenchyma; o to 2.5 micra (plate 9, fig. 4). 



Allowed to remain under the bell-jar all night and experiment continued as experiment 

 218 on April 25. 



Experiment 218. Verbena ciliata, April 25. 



Set up at 6 h 30 m p. m., April 24, remaining upon the same twigs as were used in the previous 

 experiment (214). Night temperature minimum, 50 F. 



6 h 3o m p. m., April 24, control: See 214 at the same hour. 



^h-jom a . m., April 25, control: Starch absent from chlorenchyma; abundant in guard- 

 cells; no oil; o to 3 micra. 



io h 3O m a. m., control: Oil drops large ; starch plentiful in chlorenchyma ; starch in guard- 

 cells depleted but not absent ; 2 to 4 micra. 



nh^m a. m., control: Oil drops very large; 4 to 8 micra; starch content of guard-cells 

 low, presumably at the minimum. 



Experimental part: Bell-jar maximum temperature, 95 F. ; air temperature maximum, 

 95 F ; starch in guard-cells plentiful ; plastids do not stain deep black usually, but the gran- 

 ules are often indistinguishable; no oil. In many stomata the starch is in very reduced 

 amounts. Average condition shown in the illustration (plate 9, fig. 5) ; 4 to (8) 10 micra. 



Experiment 220. Verbena ciliata. 



Red bell-jar set over twigs attached to plants at 6 a. m., April 27, and allowed to remain 

 for several days. Irrigated to keep cool. 



April 30, 6 a. m.: Oil drops small, but at normal size for this time of the morning; 2 to 

 7 micra ; starch absent from the chlorenchyma, but moderately abundant in guard-cells ; 

 plastids large usually, but not deeply staining; based on three examinations, the last with 

 KI-I, using oil immersion 1/16 and oc. 3; maximum temperature for period, 95F. (plate 

 10, fig. i). 



April 30, ii a. m., control: 4 to 10 micra; starch abundant in chlorenchyma; in small 

 amount in guard-cells. 



Experimental part: Starch in guard-cells rather meager, in about the same amount as in 

 the control; plastids smaller than at 6 a. m., otherwise appearing equally dense in staining; 

 occasional stomata with deep-staining, large plastids; starch meager in chlorenchyma; 

 4 to ii micra (plate 10, fig. 2). 



May 3, 6 a. m. : Oil drops as before, viz, small or not evident; 2 to 7 micra; moderate 

 amount of starch in guard-cells; none in chlorenchyma (plate 10, fig. 3). 



Control: Starch plentiful in guard-cells; a little in chlorenchyma. 



i i^o 111 a. m. : Maximum temperature for period, 95 F. 



Control: As usual at this hour. 



Experimental part: 6 to 13 micra; little or no starch in guard-cells; moderate amount 

 in chlorenchyma (plate 10, fig. 4). 



SUMMARY, RED LIGHT. 



Experiments begun early in the morning, when the starch content is at 

 the maximum, and concluded at the time of the normal starch minimum, 

 show that in red light 



(1) The starch in the guard-cells is reduced in amount. 



(2) Oil drops are not formed in the guard-cells. 



(3) Starch is formed in the chlorenchyma. 



(4) The stomata open. 



