THE CANE. 



4. Generally those parts of the plant undergoing cellular division contain 

 much starch and albumen and little sugar ; where cellular division is restricted 

 the reverse obtains. 



In the life history of the stalk the following phases are distinguished : 



1. In very young parts of the stalk only starch or albumen are present, 

 which are consumed little by little in the formation of cellulose. 



2. In young, rapidly-growing parts of the stalk, the cane sugar brought 

 down by the leaf is inverted, and whereas in the leaf the proportions of 

 sucrose, dextrose, and levulose were as 4 : 2 : 1, in the young joints the proportions 



X75 



FIG. 8. 



are *8 : 1 : 1. A. part of the invert sugar is used up in the formation of fibre, 

 a part unites with the amides to form albumen, and a part is deposited as 

 starch. In consequence of the inversion, the osmotic pressure is raised and 

 this tends to favour the absorption of plant food. 



3. In older joints the sucrose formed in the leaf remains unchanged 

 when it reaches the joint and the reducing sugars are used up, partly in 

 respiration, or, perhaps, are partly by a reverted enzyme action converted into 

 sucrose ; of the reducing sugars that remain, the dextrose is generally in 

 excess. 



11 



