242 



SMITH 



Table XII.— December 22, 1906. 

 Green leaf of Codiceum variegatum. 



Time . . 



Conditions 



Zero . . 



Deflection 



Temperature of junction in water 



Shade air temperature 



Temperature of junction in leaf 



Table XIII.— February 4, 1907. 

 Mature Green Leaf of Mangifera indica. 



Time 

 Conditions . . 



Zero 



Deflection . . 



Temperature of jvmction in 



water 

 Shade air temperature 

 Temperatiu-e of junction in 



leaf 



10.3 A.M. 



Sun,' still 

 00 

 3-2 



25- 1 

 25-9 



39-4 



10.15 A.M. 



Sun, still 

 00 

 30 



25-6 

 26-2 



39-2 



10.20 A.M. 



Sun, still 

 0-0 

 3-3 



26- 

 27 



40-6 



It is seen from these tables, representing experiments done 

 at different times of the year, that mature green leaves of 

 various species, varying in thickness and texture from thick 

 and fleshy {Rhceo) to quite thin {Acalypha), attain a tem- 

 perature, when normal to full sunlight and in still air, of from 

 12° C. to 16° C. above that of the surrounding air. They attain 

 an actual internal temperature of from 38° C. to 43° C. under 

 such circumstances. 



That the greater part of this large rise of temperature is due 

 to the absorption of direct sunlight is seen in the following 

 tables , which show that in the shade the temperature is always 

 much lower : — 



Table XIV. — November 14. 



