xih, c, 6 Brown and Trelease: Shrinkage and Elongation 357 



Table II. — Measurements of shoots of plant 2 of Cestrum nocturnum at 

 various hours of the day and night. 



Time. 



Tempe- 

 rature. 



P 



1.30 

 2.30 

 4.00 

 6.00 



in. 



Evapo- 

 ration 

 per 

 hour. 



ee. 



1.38 



1.20 



0.84 



0.90 



Illumination. 



Shoot 

 1. 



Sun - j 4.05 



Partial shade --.j 4.06 



Shade j 4.10 



Dusk 4.20 



[ 



7.00 



25 



0.24 



8.00 



28 



0.58 



9.00 



29 



1.34 



10.00 



31 



1.63 



11.00 



29 



1.63 



12 noon . 



30 



1.44 



p. m. 







1.00 



33 



2.30 



2.00 



33 



2.40 



3. 00 



32 



2.11 



4.00 



32 



2.21 



5.00 



30 



2.21 



6.00 



27 



1.34 



8.00 



27 



0.72 



Shade 



do 



Sun... 



... do 



Diffused light ... 

 Sun 



4.60 

 4.60 

 4.60 



4.55 

 4.60 

 4.60 



do 4-55 



Partial shade 4.60 



Shade 4-60 



do 4.60 



do - 1-60 



Dusk 4.65 



Dark I 4-70 



rements. 





Shoot 

 2. 



Condition of shoots. 



cm. 





4.55 



Much wilted. 



4.60 



Very slightly wilted. 



4.60 



Straight. 



: 4. 70 



Curved upward. 



5.00 



Do. 



5.05 



Do. 



5.00 



Slightly curved 





downward. 



5.00 



Evidently wilted. 



5.05 



Straight. 



6.00 



Slightly wilted. 



5.00 



Much wilted. 



4.95 



Slightly wilted. 



5.00 



Straight. 



5.00 



Do. 



5.05 



Curved upward. 



5.05 



Do. 



I 5.05 



Do.- 



give 

 The 



an accurate measurement of evaporation near the latter. 



shoots on the second plant were not so vigorous in ap- 

 pearance as those on the first and showed slower rates of 

 growth; wilting was, moreover, less prolonged. The shoots on 

 the second plant were first measured at 1.30 p. m., April 29, 

 and measurements were continued until 8 p. m. on the follow- 

 ing day At the time of the first measurement they were exposed 

 to direct sun and were very much wilted. An hour later they 

 were in partial shade and were only slightly wilted. At 4 

 p m they were in the shade and were straight, and at 6 p. m. 

 they were apparently very turgid and curved upward. This 

 whole period, therefore, may be considered as one during which 

 the plants were recovering from a wilted condition and during 

 it both shoots elongated 1.5 millimeters. At 7 o clock in the 

 morning the following day they were still curved upward ; one 

 had increased in length 4 millimeters and the other 3 At 8 

 o'clock they were still in the shade and still curved upward. One 

 showed no change in length, while the other had increased 5 

 millimeter. At 9 o'clock they were exposed to the direct sun. 

 Bv 10 o'clock, while still in the sun, they were evidently wilted, 



