272 



SMITH 



Another set of readings was taken on December 27 as 

 follows : — 



Table XXXVII.— December 27. 



Amherstia nobilis. 



Time. 



A.M. 



11. 5 

 11.13 

 11.21 

 11.25 

 11.27 



Black TT J .L 

 Bulb. Humidity. 



Per Cent. 



Air 

 Movement. 



Still 



Some breeze 



Still 



do. 



do. 



Average 



15 



Mature 

 Leaf. 



16-9 

 12-6 

 16-5 

 16-9 

 16-4 



•9°C. 



Young 

 Leaf. 



12-2 

 10-8 

 13-8 

 14-6 

 14-7 



13-2° C. 



Here as in Table XXXIII. there is a decidedly higher 

 temperature in the mature leaf. It must be remembered in 

 considering the differences shown in these tables that the leaves 

 used have their individual differences. Some of the young 

 leaves are more intensely coloured with anthocyan than others, 

 and differences no doubt occur according to age in the amount 

 and vitality of the chlorophyll in different mature leaves, but 

 on the whole the result is clear that the mature leaves do attain 

 a slightly and occasionally considerably higher temperature 

 than the young ones. Thus, it seems, that we have a series 

 beginning with Saraca indica, in which anthocyan is almost 

 absent, and in which the mature leaf is always higher in 

 temperature than the young leaf. Then comes Amherstia 

 nobilis with a brownish-red colour, in which the mature leaf is, 

 as a rule, only slightly higher in temperature than the young 

 leaf. Lastly, we have Theobroma Cacao with the young leaf 

 an intense pinkish-red and the mature leaf lower in tempera- 

 ture than the young leaf. 



No doubt the relative temperatures of mature and young 

 leaves are to be correlated with the amount of anthocyan in 

 the young leaf. The young leaves, without this pigment, 

 would be always cooler than the mature leaf, as is the case in 

 Saraca indica. The presence of more or less anthocyan 

 produces a temperature in the young leaf, which almost reaches 

 {Amherstia) or exceeds (Theobroma) the temperature of the 

 mature leaf. Thus the general tendency of these results is to 

 confirm and extend Stahl's conclusion that the presence of 



