14 MANUAL FOR SUGAR GROWERS. 



or three thousand gallons per acre per day in some 

 cases. The effect of this transpiration is to concen- 

 trate the crude sap, thus promoting the absorption 

 of water by the roots, and also causing free circula- 

 tion of the sap in the plant. In this way the leaf 

 acts both as a feeding and circulating organ. 



The Stem. Most plants, during their period of 

 growth, assimilate a greater quantity of material than 

 is immediately employed in building up tissues, 

 and this excess of food-material is stored away in 

 some part of the plant adapted for its accumula- 

 tion. The form in which the reserve is accumulated 

 varies ; thus there is the starch in the root of cas- 

 sava and arrowroot, oil in the seeds of various plants, 

 and in the sugar-cane sugar is stored up in the stem. 

 These reserves are generally drawn upon to meet the 

 demands of rapid growth at the times of flowering 

 and fruiting, and doubtless it is with this object that 

 the sugar-cane still accumulates sugar, though by 

 cultivation the production of seed has been dis- 

 couraged, while the tendency to secrete sugar has 

 probably been fostered and increased. 



Thus we have: 1. The root, supplying mineral 

 and nitrogenous food and w^ater. 2. The leaf, sup- 

 plying carbonaceous food under the influence of 

 sunlight, and throwing off the surplus water. 3. 

 The stem, acting as a storehouse of reserve food- 

 material, sugar. 



The reader is advised to consult a botanical text- 

 book for a more complete account of the structures 

 and functions briefly given in outline here. 



