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Figure 164. Amounts of total carbohydrates found in peanut and bean leaves at 

 intervals during the night. Comparison of residual dry weight and total nitrogen as 

 bases for calculating the change in total carbohydrates. 



Fig. 165 shows the amount of sokible sugars found in the bean and 

 peanut leaves at various periods during the night. All these are plotted 

 on the basis of data given in Table 47. 



The diurnal changes in leaves of several other plants (tobacco, salvia, 

 sunflower, hawthorn, redbud, lilac, Virginia creeper, peach, soybean, 

 cotton, grape, etc.) are reported using the twin- or half-leaf method of 

 determination. In general, herbaceous plants show much greater diurnal 

 changes than woody forms. The night changes in lilac are not measurable, 

 those in hawthorn small, those in Virginia creeper and grape considerably 

 larger, while in some herbaceous plants, as the data reported on the two 

 kinds of beans show, more than 50 per cent of the starch and sugars dis- 

 appears from the leaf during the night. In the peanut under similar condi- 

 tions the loss in these two constituents is less than 20 per cent. 



Autumn or pre-leaf fall changes in deciduous leaves. Denny ^i used the 

 twin-leaf method of sampling to study the chemical changes occurring in 



