IQip] 



CRIBBS—TILIA AMERICANA 



275 



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 i .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 1 2 : 00 

 noon. Here a saturation deficit was developed and a sudden 



a 



AH 



21L 



±11 



00 (f\oo 7100 $[00 9100 ro\oo ii[oo ijloo l\oo i\oo 3\oo vjoo }^oi i|oo yloo 



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

 II, 1918; 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 dechne 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 



