122 



BOTAMCAL GAZETTE 



[FEBRUARY 



Alcohol- water soluble fraction (F 2 ). — Table V shows a 

 distinctly higher average percentage of these extractives at the 

 higher temperature, although the order of difference is not large. 

 When, however, the composition of this fraction is examined cer- 

 tain striking differences are noted. The high temperature leaves 

 contain a much lower percentage of both total and reducing sugars 

 (table VI) and a lower percentage of polysaccharides (table VII). 

 The high temperature leaves contain about twice as much nitrogen 



(as determined by the unmodified 

 Arnold- Gunning process) as do the 

 low temperature leaves (table IX). 

 In other words, the amount of active 

 metabolic nitrogen, such as amino 

 acids, polypeptides, and simpler water 

 soluble proteins, is much higher at 

 the higher temperature. The amount 

 of nitric N is also higher at the higher 

 temperature, as was indicated when 

 the modified Arnold-Gunning process 

 was used. The results of the nitric 

 N determinations are not reported in 

 this paper. The high temperature 

 leaves also contain nearly twice the 

 percentage of alcohol-water soluble 

 phosphorus. Duplicate determina- 

 tions on one set of samples (nos. 24 

 and 87) indicated that this difference 

 was very largely due to the much 

 higher percentage of inorganic phosphorus at the higher tempera- 

 ture. These results are appended, although it is recognized that 

 more data are needed before any sweeping generalizations can be 

 made. The Powick-Chapin method was used in this determi- 

 nation. 



FlG. 16. — Influence of tem- 

 perature on maturation (photo- 

 graphed May 16): no. 12, 

 "normal" fertilization (warm 

 house); no. 74, "normal" fertili- 

 zation (cool house). 



