INTERNAL TEMPERATURE OF LEAVES. 269 



but owing to breeze only one reading was obtained in still air 

 as follows : — 



Table XXXII.— January 21, 1907. 



Here it is seen that the young pigmented leaf has a higher 

 internal temperature than the mature green leaf. This is in 

 contrast to what occurs in the case of Saraca indica, and the 

 suggestion is obvious that this difference is due to the antho- 

 cyan in the young leaves of Theobroma, this colouring being 

 absent , or almost so , from the leaves of Saraca indica. It seems 

 that in the case of this species Theobroma Cacao, the anthocyan 

 in the young leaves is more effective as an absorber of radiation 

 than the chlorophyll of the mature leaf, as is shown by the 

 higher temperature reached by the young red leaves. 



Lastly, a very large number of observations were made on 

 the temperature attained by the young leaf of Amherstia 

 nobilis compared with that attained by the mature leaf under 

 the same conditions. The young leaf is brownish-red, flaccid 

 with thin cuticle. The mature leaf is green and stiff and has a 

 thicker cuticle. 



Table XXXIII.— November 14, 1906. 

 Amherstia nobilis. — Mature leaf. 



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