DAILY MOVEMENT IN ALFALFA. 



23 



at 9 a. m. They remained in this condition an hour before beginning 

 to close, and became completely closed at 2 p. m. At 3 p. m. they 

 had opened 30 per cent and were still in this condition at 4 p. m. 

 They gradually closed to 10 per cent at 6 p. m., remained stationary 

 for two hours, and closed completely by 9 p. m. The lower stomata 

 remained closed from noon until 5 p. m., after which they opened 

 slowly to 10 per cent at 7 p. m. At 8 p. m. they again closed, to remain 

 so until 9 p. m. By 10 p. m. the stomata of both surfaces opened 

 5 per cent, the upper remaining in this condition to the next hour, 

 while the lower opened to 15 per cent. At midnight the lower were 

 closed, but the upper commenced opening again, reaching 15 per 

 cent at 1 a. m., after which they closed slowly once more, this being 



IOO 

 90 

 80 

 70 

 60 



5 6 7 e 9 IO II NOON I 



B 6 7 8 9 rO II MT. I t 3 



Fio. 6. Series 26, showing movement in upper etomata of alfalfa (A), 

 sunlight (B). 



4.5678910 II NOON I Z3456789IOII 



.I I 3 * 



FIG. 7. Series 10, weather data for June 8-9, 1916, sunlight (A), 

 humidity (B), temperature (C). 



completed by 3 a. m. The lower stomata continued closed from 

 midnight to 3 a. m. After this hour the stomata of both surfaces 

 opened, reaching the same degree of opening at 4 a. m., as on the 

 preceding day. The stomata in the epiderm of the stems were 

 somewhat longer and narrower than those of the upper epiderm of 

 the leaves. They seemed to run lengthwise on the stem in all cases. 

 Their behavior agreed with that of the upper stomata, except that 

 maximum morning opening continued until 8 a. m. when they closed 



