300 



The Carbohiid Idles of thr MaiKjobl Lxif 



to be due to the transformation of reserve substances (gums) into sugars, 

 finds its counterpart in the stalk curve (Fig. 9) in the increase of the 

 hexoses which starts at night at about 11 p.m. and continues until 

 sunrise ; this increase of the sugars in the stalks, occurring moderately 

 rapidlv between 11 p.m. and 1 a.m., and then far more rapidly from 

 4 a.m. to (3 a.m., exactly corresponds with the rising portion of the sugar 

 curves in Fig. 5 from 8 p.m. to 2 a.m., followed by the rapid fall from 



Day 



Night 



Fig. 10. Mangold mid-ribs. Sc-rira II, Sept. 10-11, 1912. 



the maxima B and B' , which occurs between 2 a.m. and 6 a.m. The 

 rapid fall of the sugars in the leaf is no doubt largely due to their trans- 

 location from the leaf to the top of the stalks. It is important to observe 

 (comparing Figs. 9 and 10) that, as might be anticipated if the sugars are 

 formed in the leaf tissue and are thence conveyed to the mid-ribs and 

 stalks, the movement of the sugars in the mid-ribs is always in advance 



