PENTOSE SUGARS IN PLANT METABOLISM 



375 



normally. The analyses are given in table 2 in terms of the per 

 cent of the dry material. The first young joints were 2 to 4 

 cm., about fifteen days old. It is evident that the amount of 

 pentose sugar is considerable even in this very early stage, al- 



TABLE 2 

 The carbohydrate content of young and mature Opuntia Joints. 



percentages of the dry material 



Values given in 



March 27 1 



April 3 



April 16 ( 



a 



IB 

 < 



6.88 

 12.60 



7.51 

 14.40 



10.71 

 13.95 



though the proportion to the total sugars is somewhat higher in 

 the parent joints. 



An analysis made in October comparing the young joints, 

 then fully matured, with joints three years old show that there 



TABLE 3 

 Carbohydrate content of young and old joints of the same plant 



CO a 

 z s z 



M a* M 



1916 

 1913 



D a 

 ■J to 



a J 



9.10 

 10.26 



TABLE 4 



Daily variation in carbohydrate content of Opuntia sp. in October 



5.00 p.m. 

 7.30 a.m. 

 5.00 p.m. 



TOTAL 



SUGAR.S TO 



TOTAL 



PENTOSE 



0.531 

 0.430 

 0.478 



