1919] 



CRIBBS—TIUA A MERIC. 1 .V. 1 



2 75 



A very different behavior occurred at station E, where the 

 exposure is more intense. The growth water here was found to 

 be 0.679 per cent at 2 dm. and 1 .054 per cent at 3 dm., but the 

 leaves remained turgid throughout the day, and there was no 

 visible wilting. The transpiration index at 6:00 a.m. was quite 

 high, and rose rapidly during the morning to a maximum at 12:00 

 noon. Here a saturation deficit was developed and a sudden 



LO 



11 

 2.21 



±11 



n 



Wo T\oo ftoo 9100 W\oo u\oo a\oo i[oo i\oo JT»° i\oo i\o6 T^oo Jtfo" 



Fig. 9. — Graphs for stations A, B, and C on August 26 and station E on August 

 11, 191 8; high transpiration index occurs on open sand with afternoon saturation 

 deficit, while indices for humus stations remain low, due to visible wilting. 



depression occurred until about 3:00 p.m., which was followed 

 by a second low mode at 4:30. 



This curve is a very typical one for a clear day at this position, 

 in that there is a rapid rise in the morning to a high maximum, 

 and a following clearly marked depression due to a saturation 

 deficit, but no visible wilting occurs; then a second low mode in 

 the afternoon about 4:00 p.m., followed by a rapid decline with 

 the closing of the stomata in the evening. The morning maxi- 

 mum occurs from 9 : 00 to 1 2 : 00, unless disturbed in some way by 



