108 BOTANICAL GAZETTE [AUGUST 
made to ascertain whether or not the stomata were partially 
closed or whether there was an increased opening after a period of 
2 hours, as has been shown for certain plants by Irjrn (20). At 
any rate, the time interval in the case of intensely wilted Helianthus 
plants is much smaller. Even if the stomata should be partially 
TABLE VIII 
POROMETER READINGS TAKEN OF A WILTING stag 
PLANT GROWING WHERE EVAPORATING POWE 
OF LOW 
AIR IS 
Rate of evapora- | Rate of flow, tim 
pret oe pr ea jtion from tia antl gg real in rhino 
me gro ey between succes- 
r hour sive F bubbles 
December 31 16:00. 0200 ee 
Ui bd a le CAG hee ee cae Oa 
12) 16:30... i eee Por eee 
10:30... Co ©. MIDIS Tere te pea are eee 
13} 14:30.. OOG re Pires een 
20:00.. ORG ee eae 
10:30 0.37 257 
I4} 14:30 0.66 360 
20:00 0.34 352 
10:30. ©.30 318 
I5414:00. 0.36 300 
20:00, ©.40 335 
16:30: 0.43 357 
164 14:30.. 0.43 348 
20:00. 0.49 343 
10:30. 0.40 341 
17} 14:30. 0.44 365 
20:00 0.37 343 
10 0.34 308 
18; 14:30 0.44 389 
20 0.39 360 
closed, the results obtained from tables VII and VIII show that 
during the march of wilting, where the plant acquires its perma- 
nent wilting point, the stomatal opening does not enter in to affect 
the diffusion or transpirational water loss. This statement is in 
agreement with that of DARwin, that when the transpiration is 
high and the supply water insufficient the lack of water is a more 
important factor than stomatal changes. It would be extremely 
advantageous, however, to have the stomatal movement question 
